diff --git a/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageGrpcMetricsInterceptor.java b/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageGrpcMetricsInterceptor.java
index c2b36f5f8c9f..06ccb3a37330 100644
--- a/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageGrpcMetricsInterceptor.java
+++ b/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageGrpcMetricsInterceptor.java
@@ -61,11 +61,18 @@ final class StorageGrpcMetricsInterceptor implements ClientInterceptor {
   @Override
   public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(
       MethodDescriptor<ReqT, RespT> method, CallOptions callOptions, Channel next) {
-    if (metrics == null || metrics.getRpcClientCallDuration() == null) {
+    if (metrics == null) {
       return next.newCall(method, callOptions);
     }
 
     String shortMethod = extractShortMethodName(method.getFullMethodName());
+    boolean isReadMethod = "ReadObject".equals(shortMethod) || "BidiReadObject".equals(shortMethod);
+    boolean recordDuration = metrics.getRpcClientCallDuration() != null;
+    boolean recordTtfb = isReadMethod && metrics.getTtfb() != null;
+    if (!recordDuration && !recordTtfb) {
+      return next.newCall(method, callOptions);
+    }
+
     String resolvedServerAddress =
         defaultServerAddress != null
             ? defaultServerAddress
@@ -79,14 +86,28 @@ public <ReqT, RespT> ClientCall<ReqT, RespT> interceptCall(
       public void start(Listener<RespT> responseListener, Metadata headers) {
         long startTimeNanos = clock.nanoTime();
         AtomicBoolean callRecorded = new AtomicBoolean(false);
+        AtomicBoolean ttfbRecorded = new AtomicBoolean(false);
 
         super.start(
             new SimpleForwardingClientCallListener<RespT>(responseListener) {
+              @Override
+              public void onMessage(RespT message) {
+                // The first response message from the server (including metadata-only
+                // responses for 0-byte objects) marks Time To First Byte (TTFB).
+                if (recordTtfb && ttfbRecorded.compareAndSet(false, true)) {
+                  double ttfbSeconds =
+                      Math.max(0.0, (clock.nanoTime() - startTimeNanos) / 1_000_000_000.0);
+                  String networkPath = detectNetworkPath(getAttributes(), isDirectPathEndpoint);
+                  StorageMetricsContext.recordTtfb(
+                      metrics, metricsCtx, ttfbSeconds, "grpc", networkPath, serverAddress);
+                }
+                super.onMessage(message);
+              }
+
               @Override
               public void onClose(Status status, Metadata trailers) {
                 try {
-                  if (callRecorded.compareAndSet(false, true)
-                      && metrics.getRpcClientCallDuration() != null) {
+                  if (recordDuration && callRecorded.compareAndSet(false, true)) {
                     double durationSeconds =
                         Math.max(0.0, (clock.nanoTime() - startTimeNanos) / 1_000_000_000.0);
                     String networkPath = detectNetworkPath(getAttributes(), isDirectPathEndpoint);
diff --git a/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageHttpMetricsInterceptor.java b/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageHttpMetricsInterceptor.java
index b032ff77529e..6df7382a1b6b 100644
--- a/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageHttpMetricsInterceptor.java
+++ b/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageHttpMetricsInterceptor.java
@@ -61,7 +61,12 @@ public void initialize(HttpRequest request) throws IOException {
     if (delegate != null) {
       delegate.initialize(request);
     }
-    if (metrics == null || metrics.getHttpClientRequestDuration() == null) {
+    if (metrics == null) {
+      return;
+    }
+    boolean recordDuration = metrics.getHttpClientRequestDuration() != null;
+    boolean recordTtfb = metrics.getTtfb() != null;
+    if (!recordDuration && !recordTtfb) {
       return;
     }
 
@@ -88,26 +93,48 @@ public void initialize(HttpRequest request) throws IOException {
           }
           if (recorded.compareAndSet(false, true)) {
             int statusCode = response.getStatusCode();
-            String errorType =
-                statusCode >= 400
-                    ? StorageErrorTypeMapper.mapHttpResponseCode(statusCode)
-                    : StorageErrorTypeMapper.STATUS_OK;
-            recordDuration(request, startTimeNanos.get(), String.valueOf(statusCode), errorType);
+            long startNanos = startTimeNanos.get();
+            if (recordDuration) {
+              String errorType =
+                  statusCode >= 400
+                      ? StorageErrorTypeMapper.mapHttpResponseCode(statusCode)
+                      : StorageErrorTypeMapper.STATUS_OK;
+              recordDuration(request, startNanos, String.valueOf(statusCode), errorType);
+            }
+            // Evaluate isMediaDownloadRequest(request) at response time rather than in
+            // initialize(HttpRequest), because callers such as MediaHttpDownloader may append
+            // query parameters (e.g. alt=media) to request.getUrl() after buildGetRequest().
+            if (recordTtfb
+                && statusCode >= 200
+                && statusCode < 300
+                && isMediaDownloadRequest(request)) {
+              double ttfbSeconds = Math.max(0.0, (clock.nanoTime() - startNanos) / 1_000_000_000.0);
+              String serverAddress = resolveServerAddress(request.getUrl(), defaultServerAddress);
+              StorageMetricsContext.recordTtfb(
+                  metrics,
+                  null,
+                  ttfbSeconds,
+                  "http",
+                  StorageClientMetrics.NETWORK_PATH_CLOUDPATH,
+                  serverAddress);
+            }
           }
         });
 
-    // HttpIOExceptionHandler does not receive the thrown IOException instance from
-    // google-http-client, so transport-level IOExceptions default to STATUS_CONNECTIVITY here
-    // (specific subtypes like TIMEOUT, DNS_FAILURE, and TLS_FAILURE are mapped in Retrying).
-    request.setIOExceptionHandler(
-        (req, supportsRetry) -> {
-          if (recorded.compareAndSet(false, true)) {
-            recordDuration(
-                req, startTimeNanos.get(), "0", StorageErrorTypeMapper.STATUS_CONNECTIVITY);
-          }
-          return existingIoHandler != null
-              && existingIoHandler.handleIOException(req, supportsRetry);
-        });
+    if (recordDuration) {
+      // HttpIOExceptionHandler does not receive the thrown IOException instance from
+      // google-http-client, so transport-level IOExceptions default to STATUS_CONNECTIVITY here
+      // (specific subtypes like TIMEOUT, DNS_FAILURE, and TLS_FAILURE are mapped in Retrying).
+      request.setIOExceptionHandler(
+          (req, supportsRetry) -> {
+            if (recorded.compareAndSet(false, true)) {
+              recordDuration(
+                  req, startTimeNanos.get(), "0", StorageErrorTypeMapper.STATUS_CONNECTIVITY);
+            }
+            return existingIoHandler != null
+                && existingIoHandler.handleIOException(req, supportsRetry);
+          });
+    }
   }
 
   private void recordDuration(
@@ -182,6 +209,19 @@ static String extractUrlTemplate(@Nullable GenericUrl url) {
     return parts.length == 1 ? "/{bucket}" : "/{bucket}/{object}";
   }
 
+  static boolean isMediaDownloadRequest(@Nullable HttpRequest request) {
+    if (request == null) {
+      return false;
+    }
+    if (!"GET".equalsIgnoreCase(request.getRequestMethod()) || request.getUrl() == null) {
+      return false;
+    }
+    GenericUrl url = request.getUrl();
+    String path = url.getRawPath();
+    return (path != null && path.startsWith("/download/storage/v1/"))
+        || "media".equals(url.getFirst("alt"));
+  }
+
   private static String extractV1UrlTemplate(String rest) {
     String[] segments = rest.split("/");
     if (segments.length >= 2 && "b".equals(segments[0])) {
diff --git a/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageMetricsContext.java b/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageMetricsContext.java
index 9caf52d602cb..4398657793f4 100644
--- a/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageMetricsContext.java
+++ b/java-storage/google-cloud-storage/src/main/java/com/google/cloud/storage/StorageMetricsContext.java
@@ -321,6 +321,34 @@ static void recordHttpRequestDuration(
     metrics.getHttpClientRequestDuration().record(durationSeconds, attributes, Context.current());
   }
 
+  static void recordTtfb(
+      @Nullable StorageClientMetrics metrics,
+      @Nullable StorageMetricsContext metricsContext,
+      double ttfbSeconds,
+      String rpcSystemName,
+      String networkPath,
+      @Nullable String serverAddress) {
+    if (metrics == null || metrics.getTtfb() == null) {
+      return;
+    }
+    Context otelContext =
+        metricsContext != null ? metricsContext.getOtelContext() : Context.current();
+    String operationName =
+        metricsContext != null && metricsContext.getOperationName() != null
+            ? metricsContext.getOperationName()
+            : "ReadObject";
+    Attributes attributes =
+        metrics
+            .clientAttributesBuilder()
+            .put(StorageClientMetrics.KEY_RPC_SYSTEM_NAME, rpcSystemName)
+            .put(StorageClientMetrics.KEY_GCP_STORAGE_OPERATION, operationName)
+            .put(StorageClientMetrics.KEY_NETWORK_PATH, networkPath)
+            .put(
+                StorageClientMetrics.KEY_SERVER_ADDRESS, serverAddress != null ? serverAddress : "")
+            .build();
+    metrics.getTtfb().record(ttfbSeconds, attributes, otelContext);
+  }
+
   private Attributes buildAttemptBaseAttributes(StorageClientMetrics metrics) {
     AttributesBuilder baseBuilder = Attributes.builder();
     baseBuilder.putAll(metrics.getClientAttributes());
diff --git a/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageGrpcMetricsInterceptorTest.java b/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageGrpcMetricsInterceptorTest.java
index 214bb5462175..f80ec35e7ea9 100644
--- a/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageGrpcMetricsInterceptorTest.java
+++ b/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageGrpcMetricsInterceptorTest.java
@@ -59,6 +59,22 @@ public final class StorageGrpcMetricsInterceptorTest {
           .setResponseMarshaller(new NoopMarshaller())
           .build();
 
+  private static final MethodDescriptor<Void, Void> BIDI_READ_OBJECT_METHOD =
+      MethodDescriptor.<Void, Void>newBuilder()
+          .setType(MethodDescriptor.MethodType.BIDI_STREAMING)
+          .setFullMethodName("google.storage.v2.Storage/BidiReadObject")
+          .setRequestMarshaller(new NoopMarshaller())
+          .setResponseMarshaller(new NoopMarshaller())
+          .build();
+
+  private static final MethodDescriptor<Void, Void> WRITE_OBJECT_METHOD =
+      MethodDescriptor.<Void, Void>newBuilder()
+          .setType(MethodDescriptor.MethodType.CLIENT_STREAMING)
+          .setFullMethodName("google.storage.v2.Storage/WriteObject")
+          .setRequestMarshaller(new NoopMarshaller())
+          .setResponseMarshaller(new NoopMarshaller())
+          .build();
+
   private InMemoryMetricReader reader;
   private SdkMeterProvider meterProvider;
   private FakeClock clock;
@@ -217,6 +233,134 @@ public void interceptCall_callFails_recordsErrorType() throws Exception {
         .isEqualTo("NOT_FOUND");
     assertThat(point.getAttributes().get(StorageClientMetrics.KEY_SERVER_ADDRESS))
         .isEqualTo("storage.googleapis.com");
+
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+    assertThat(ttfbData).isNull();
+  }
+
+  @Test
+  public void interceptCall_readObject_recordsTtfbOnFirstMessage() throws Exception {
+    StorageClientMetrics metrics = StorageClientMetrics.create(meterProvider, true, false);
+    StorageGrpcMetricsInterceptor interceptor =
+        new StorageGrpcMetricsInterceptor(metrics, clock, "storage.googleapis.com");
+
+    TestClientCall<Void, Void> testCall = new TestClientCall<>(io.grpc.Attributes.EMPTY);
+    TestChannel testChannel = new TestChannel(testCall, "storage.googleapis.com");
+
+    ClientCall<Void, Void> call =
+        interceptor.interceptCall(READ_OBJECT_METHOD, CallOptions.DEFAULT, testChannel);
+    call.start(new TestListener<>(), new Metadata());
+
+    clock.advanceNanos(200_000_000L); // 0.2s
+    testCall.deliverMessage(null); // First response message: triggers TTFB
+
+    clock.advanceNanos(300_000_000L); // 0.3s more (total 0.5s)
+    testCall.deliverMessage(null); // Second message: should NOT record TTFB again
+    testCall.close(Status.OK, new Metadata());
+
+    Collection<MetricData> metricData = reader.collectAllMetrics();
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+
+    assertThat(ttfbData).isNotNull();
+    assertThat(ttfbData.getHistogramData().getPoints()).hasSize(1);
+    HistogramPointData ttfbPoint = ttfbData.getHistogramData().getPoints().iterator().next();
+    assertThat(ttfbPoint.getCount()).isEqualTo(1L);
+    assertThat(ttfbPoint.getSum()).isWithin(1e-6).of(0.2);
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_RPC_SYSTEM_NAME))
+        .isEqualTo("grpc");
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_GCP_STORAGE_OPERATION))
+        .isEqualTo("ReadObject");
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_NETWORK_PATH))
+        .isEqualTo(StorageClientMetrics.NETWORK_PATH_UNKNOWN);
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_SERVER_ADDRESS))
+        .isEqualTo("storage.googleapis.com");
+
+    MetricData durationData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_RPC_CLIENT_CALL_DURATION))
+            .findFirst()
+            .orElse(null);
+    assertThat(durationData).isNotNull();
+    HistogramPointData durationPoint =
+        durationData.getHistogramData().getPoints().iterator().next();
+    assertThat(durationPoint.getSum()).isWithin(1e-6).of(0.5);
+  }
+
+  @Test
+  public void interceptCall_bidiReadObject_recordsTtfbOnFirstMessageWithUnifiedOperation()
+      throws Exception {
+    StorageClientMetrics metrics = StorageClientMetrics.create(meterProvider, true, false);
+    StorageGrpcMetricsInterceptor interceptor =
+        new StorageGrpcMetricsInterceptor(metrics, clock, "google-c2p:///storage.googleapis.com");
+
+    TestClientCall<Void, Void> testCall = new TestClientCall<>(io.grpc.Attributes.EMPTY);
+    TestChannel testChannel = new TestChannel(testCall, "storage.googleapis.com");
+
+    ClientCall<Void, Void> call =
+        interceptor.interceptCall(BIDI_READ_OBJECT_METHOD, CallOptions.DEFAULT, testChannel);
+    call.start(new TestListener<>(), new Metadata());
+
+    clock.advanceNanos(150_000_000L); // 0.15s
+    testCall.deliverMessage(null);
+
+    clock.advanceNanos(250_000_000L); // 0.25s more (total 0.4s)
+    testCall.deliverMessage(null);
+    testCall.close(Status.OK, new Metadata());
+
+    Collection<MetricData> metricData = reader.collectAllMetrics();
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+
+    assertThat(ttfbData).isNotNull();
+    assertThat(ttfbData.getHistogramData().getPoints()).hasSize(1);
+    HistogramPointData ttfbPoint = ttfbData.getHistogramData().getPoints().iterator().next();
+    assertThat(ttfbPoint.getCount()).isEqualTo(1L);
+    assertThat(ttfbPoint.getSum()).isWithin(1e-6).of(0.15);
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_RPC_SYSTEM_NAME))
+        .isEqualTo("grpc");
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_GCP_STORAGE_OPERATION))
+        .isEqualTo("ReadObject");
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_NETWORK_PATH))
+        .isEqualTo(StorageClientMetrics.NETWORK_PATH_DIRECTPATH);
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_SERVER_ADDRESS))
+        .isEqualTo("storage.googleapis.com");
+  }
+
+  @Test
+  public void interceptCall_nonReadMethod_doesNotRecordTtfb() throws Exception {
+    StorageClientMetrics metrics = StorageClientMetrics.create(meterProvider, true, false);
+    StorageGrpcMetricsInterceptor interceptor =
+        new StorageGrpcMetricsInterceptor(metrics, clock, "storage.googleapis.com");
+
+    TestClientCall<Void, Void> testCall = new TestClientCall<>(io.grpc.Attributes.EMPTY);
+    TestChannel testChannel = new TestChannel(testCall, "storage.googleapis.com");
+
+    ClientCall<Void, Void> call =
+        interceptor.interceptCall(WRITE_OBJECT_METHOD, CallOptions.DEFAULT, testChannel);
+    call.start(new TestListener<>(), new Metadata());
+
+    clock.advanceNanos(200_000_000L);
+    testCall.deliverMessage(null);
+    testCall.close(Status.OK, new Metadata());
+
+    Collection<MetricData> metricData = reader.collectAllMetrics();
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+    assertThat(ttfbData).isNull();
   }
 
   @Test
@@ -499,6 +643,12 @@ public Attributes getAttributes() {
       return attributes;
     }
 
+    void deliverMessage(RespT message) {
+      if (listener != null) {
+        listener.onMessage(message);
+      }
+    }
+
     void close(Status status, Metadata trailers) {
       if (listener != null) {
         listener.onClose(status, trailers);
diff --git a/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageHttpMetricsInterceptorTest.java b/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageHttpMetricsInterceptorTest.java
index 25cd88f605b9..3cc76448f5d2 100644
--- a/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageHttpMetricsInterceptorTest.java
+++ b/java-storage/google-cloud-storage/src/test/java/com/google/cloud/storage/StorageHttpMetricsInterceptorTest.java
@@ -397,6 +397,198 @@ public LowLevelHttpResponse execute() throws IOException {
         .isEqualTo("storage.googleapis.com");
   }
 
+  @Test
+  public void isMediaDownloadRequest_cases() throws IOException {
+    HttpTransport transport = new MockHttpTransport();
+    HttpRequest getDownload =
+        transport
+            .createRequestFactory()
+            .buildGetRequest(
+                new GenericUrl(
+                    "https://storage.googleapis.com/download/storage/v1/b/my-b/o/my-obj"));
+    assertThat(StorageHttpMetricsInterceptor.isMediaDownloadRequest(getDownload)).isTrue();
+
+    HttpRequest getAltMedia =
+        transport
+            .createRequestFactory()
+            .buildGetRequest(
+                new GenericUrl(
+                    "https://storage.googleapis.com/storage/v1/b/my-b/o/my-obj?alt=media"));
+    assertThat(StorageHttpMetricsInterceptor.isMediaDownloadRequest(getAltMedia)).isTrue();
+
+    HttpRequest getMetadata =
+        transport
+            .createRequestFactory()
+            .buildGetRequest(
+                new GenericUrl("https://storage.googleapis.com/storage/v1/b/my-b/o/my-obj"));
+    assertThat(StorageHttpMetricsInterceptor.isMediaDownloadRequest(getMetadata)).isFalse();
+
+    HttpRequest postReq =
+        transport
+            .createRequestFactory()
+            .buildPostRequest(
+                new GenericUrl(
+                    "https://storage.googleapis.com/download/storage/v1/b/my-b/o/my-obj"),
+                null);
+    assertThat(StorageHttpMetricsInterceptor.isMediaDownloadRequest(postReq)).isFalse();
+
+    assertThat(StorageHttpMetricsInterceptor.isMediaDownloadRequest(null)).isFalse();
+  }
+
+  @Test
+  public void initialize_mediaDownload_recordsTtfb() throws IOException {
+    StorageClientMetrics metrics = StorageClientMetrics.create(meterProvider, true, false);
+    StorageHttpMetricsInterceptor interceptor =
+        new StorageHttpMetricsInterceptor(null, metrics, clock, "https://storage.googleapis.com");
+
+    MockLowLevelHttpResponse lowLevelResponse = new MockLowLevelHttpResponse();
+    lowLevelResponse.setStatusCode(200);
+    HttpTransport transport =
+        new MockHttpTransport() {
+          @Override
+          public LowLevelHttpRequest buildRequest(String method, String url) {
+            return new MockLowLevelHttpRequest() {
+              @Override
+              public LowLevelHttpResponse execute() throws IOException {
+                clock.advanceNanos(250_000_000L); // 0.25s network duration
+                return lowLevelResponse;
+              }
+            };
+          }
+        };
+
+    HttpRequest request =
+        transport
+            .createRequestFactory(interceptor)
+            .buildGetRequest(
+                new GenericUrl(
+                    "https://storage.googleapis.com/download/storage/v1/b/my-b/o/my-obj"));
+    request.execute();
+
+    Collection<MetricData> metricData = reader.collectAllMetrics();
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+
+    assertThat(ttfbData).isNotNull();
+    assertThat(ttfbData.getHistogramData().getPoints()).hasSize(1);
+    HistogramPointData ttfbPoint = ttfbData.getHistogramData().getPoints().iterator().next();
+    assertThat(ttfbPoint.getCount()).isEqualTo(1L);
+    assertThat(ttfbPoint.getSum()).isWithin(1e-6).of(0.25);
+    Attributes attrs = ttfbPoint.getAttributes();
+    assertThat(attrs.get(StorageClientMetrics.KEY_RPC_SYSTEM_NAME)).isEqualTo("http");
+    assertThat(attrs.get(StorageClientMetrics.KEY_GCP_STORAGE_OPERATION)).isEqualTo("ReadObject");
+    assertThat(attrs.get(StorageClientMetrics.KEY_NETWORK_PATH))
+        .isEqualTo(StorageClientMetrics.NETWORK_PATH_CLOUDPATH);
+    assertThat(attrs.get(StorageClientMetrics.KEY_SERVER_ADDRESS))
+        .isEqualTo("storage.googleapis.com");
+  }
+
+  @Test
+  public void initialize_mediaDownloadNon2xxResponse_doesNotRecordTtfb() throws IOException {
+    StorageClientMetrics metrics = StorageClientMetrics.create(meterProvider, true, false);
+    StorageHttpMetricsInterceptor interceptor =
+        new StorageHttpMetricsInterceptor(null, metrics, clock, "https://storage.googleapis.com");
+
+    for (int statusCode : new int[] {304, 404}) {
+      MockLowLevelHttpResponse lowLevelResponse = new MockLowLevelHttpResponse();
+      lowLevelResponse.setStatusCode(statusCode);
+      HttpTransport transport =
+          new MockHttpTransport.Builder().setLowLevelHttpResponse(lowLevelResponse).build();
+
+      HttpRequest request =
+          transport
+              .createRequestFactory(interceptor)
+              .buildGetRequest(
+                  new GenericUrl(
+                      "https://storage.googleapis.com/download/storage/v1/b/my-b/o/my-obj?alt=media"));
+      request.setThrowExceptionOnExecuteError(false);
+      request.execute();
+    }
+
+    Collection<MetricData> metricData = reader.collectAllMetrics();
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+    assertThat(ttfbData).isNull();
+  }
+
+  @Test
+  public void initialize_altMediaAddedAfterBuildGetRequest_recordsTtfb() throws IOException {
+    StorageClientMetrics metrics = StorageClientMetrics.create(meterProvider, true, false);
+    StorageHttpMetricsInterceptor interceptor =
+        new StorageHttpMetricsInterceptor(null, metrics, clock, "https://storage.googleapis.com");
+
+    MockLowLevelHttpResponse lowLevelResponse = new MockLowLevelHttpResponse();
+    lowLevelResponse.setStatusCode(200);
+    HttpTransport transport =
+        new MockHttpTransport() {
+          @Override
+          public LowLevelHttpRequest buildRequest(String method, String url) {
+            return new MockLowLevelHttpRequest() {
+              @Override
+              public LowLevelHttpResponse execute() {
+                clock.advanceNanos(120_000_000L);
+                return lowLevelResponse;
+              }
+            };
+          }
+        };
+
+    HttpRequest request =
+        transport
+            .createRequestFactory(interceptor)
+            .buildGetRequest(
+                new GenericUrl("https://storage.googleapis.com/storage/v1/b/my-b/o/my-obj"));
+    request.getUrl().put("alt", "media");
+    request.execute();
+
+    Collection<MetricData> metricData = reader.collectAllMetrics();
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+
+    assertThat(ttfbData).isNotNull();
+    HistogramPointData ttfbPoint = ttfbData.getHistogramData().getPoints().iterator().next();
+    assertThat(ttfbPoint.getCount()).isEqualTo(1L);
+    assertThat(ttfbPoint.getSum()).isWithin(1e-6).of(0.12);
+    assertThat(ttfbPoint.getAttributes().get(StorageClientMetrics.KEY_GCP_STORAGE_OPERATION))
+        .isEqualTo("ReadObject");
+  }
+
+  @Test
+  public void initialize_nonDownloadGet_doesNotRecordTtfb() throws IOException {
+    StorageClientMetrics metrics = StorageClientMetrics.create(meterProvider, true, false);
+    StorageHttpMetricsInterceptor interceptor =
+        new StorageHttpMetricsInterceptor(null, metrics, clock, "https://storage.googleapis.com");
+
+    MockLowLevelHttpResponse lowLevelResponse = new MockLowLevelHttpResponse();
+    lowLevelResponse.setStatusCode(200);
+    HttpTransport transport =
+        new MockHttpTransport.Builder().setLowLevelHttpResponse(lowLevelResponse).build();
+
+    HttpRequest request =
+        transport
+            .createRequestFactory(interceptor)
+            .buildGetRequest(
+                new GenericUrl("https://storage.googleapis.com/storage/v1/b/my-b/o/my-obj"));
+    request.execute();
+
+    Collection<MetricData> metricData = reader.collectAllMetrics();
+    MetricData ttfbData =
+        metricData.stream()
+            .filter(m -> m.getName().equals(StorageClientMetrics.METRIC_GCP_STORAGE_CLIENT_TTFB))
+            .findFirst()
+            .orElse(null);
+    assertThat(ttfbData).isNull();
+  }
+
   @Test
   public void initialize_ioExceptionBeforeExecuteInterceptorRuns_doesNotRecordMetric()
       throws IOException {