diff --git a/blackjackbot/commands/game/commands.py b/blackjackbot/commands/game/commands.py
index 5b25a09..3a884aa 100644
--- a/blackjackbot/commands/game/commands.py
+++ b/blackjackbot/commands/game/commands.py
@@ -18,10 +18,10 @@ def start_cmd(update, context):
     """Handles messages contianing the /start command. Starts a game for a specific user"""
     user = update.effective_user
     chat = update.effective_chat
-    lang_id = Database().get_lang_id(chat.id)
-    translator = Translator(lang_id=lang_id)
 
     Database().add_user(user.id, user.language_code, user.first_name, user.last_name, user.username)
+    # Use the language of the user's Telegram client for chats without a language yet, e.g. new groups
+    Database().set_default_lang_id(chat.id, user.language_code)
 
     try:
         GameStore().get_game(update.effective_chat.id)
diff --git a/blackjackbot/commands/game/tests/commands_test.py b/blackjackbot/commands/game/tests/commands_test.py
index 82c34f1..b6bb965 100644
--- a/blackjackbot/commands/game/tests/commands_test.py
+++ b/blackjackbot/commands/game/tests/commands_test.py
@@ -3,7 +3,7 @@
 from unittest.mock import Mock, patch
 
 from blackjack.game import BlackJackGame
-from blackjackbot.commands.game.commands import join_callback
+from blackjackbot.commands.game.commands import join_callback, start_cmd
 from blackjackbot.gamestore import GameStore
 
 
@@ -38,6 +38,25 @@ def test_join_callback_stores_user(self, db_mock, decorator_db_mock):
         self.assertEqual(2, len(game.players))
         db_mock.return_value.add_user.assert_called_once_with(2, "de", "B", "Bee", "bbb")
 
+    @patch("blackjackbot.commands.game.commands.create_game")
+    @patch("blackjackbot.commands.game.commands.Database")
+    def test_start_cmd_uses_telegram_language(self, db_mock, create_game_mock):
+        """Starting a game must store the user's Telegram language for the chat before the game is created"""
+        chat_id = -1001234
+
+        update = Mock()
+        update.effective_chat.id = chat_id
+        update.effective_user.id = 2
+        update.effective_user.first_name = "B"
+        update.effective_user.last_name = "Bee"
+        update.effective_user.username = "bbb"
+        update.effective_user.language_code = "de"
+
+        create_game_mock.side_effect = lambda *args: db_mock.return_value.set_default_lang_id.assert_called_once_with(chat_id, "de")
+        start_cmd(update, Mock())
+
+        create_game_mock.assert_called_once()
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/database/database.py b/database/database.py
index 82ee9a1..3e83323 100644
--- a/database/database.py
+++ b/database/database.py
@@ -170,6 +170,14 @@ def set_lang_id(self, chat_id, lang_id):
             self.cursor.execute("UPDATE chats SET lang_id = ? WHERE chat_id = ?;", [lang_id, chat_id])
         self.connection.commit()
 
+    def set_default_lang_id(self, chat_id, lang_id):
+        """Stores the language for a chat, unless the chat already got a language (e.g. chosen via /language)"""
+        if not lang_id:
+            return
+        Cache().invalidate_lang_cache(chat_id)
+        self.cursor.execute("INSERT OR IGNORE INTO chats (chat_id, lang_id) VALUES(?, ?);", [chat_id, lang_id.lower()])
+        self.connection.commit()
+
     def add_user(self, user_id, lang_id, first_name, last_name, username):
         if self.is_user_saved(user_id):
             return
diff --git a/database/tests/database_test.py b/database/tests/database_test.py
index 568ca9d..681f604 100644
--- a/database/tests/database_test.py
+++ b/database/tests/database_test.py
@@ -51,6 +51,30 @@ def test_add_user_with_existing_chat(self):
         self.db.cursor.execute("SELECT lang_id FROM chats WHERE chat_id=?;", [str(self.user_id)])
         self.assertEqual("de", self.db.cursor.fetchone()["lang_id"])
 
+    def test_set_default_lang_id_new_chat(self):
+        """Chats without a language must use the language_code sent by Telegram"""
+        self.assertEqual("en", self.db.get_lang_id(self.user_id))
+
+        self.db.set_default_lang_id(self.user_id, "DE")
+
+        # The cached default language must not be returned anymore
+        self.assertEqual("de", self.db.get_lang_id(self.user_id))
+
+    def test_set_default_lang_id_existing_chat(self):
+        """A language which was already set for a chat (e.g. via /language) must not be overwritten"""
+        self.db.set_lang_id(chat_id=self.user_id, lang_id="nl")
+
+        self.db.set_default_lang_id(self.user_id, "de")
+
+        self.assertEqual("nl", self.db.get_lang_id(self.user_id))
+
+    def test_set_default_lang_id_without_language_code(self):
+        """Telegram does not always send a language_code, so nothing must be stored then"""
+        self.db.set_default_lang_id(self.user_id, None)
+
+        self.db.cursor.execute("SELECT lang_id FROM chats WHERE chat_id=?;", [str(self.user_id)])
+        self.assertIsNone(self.db.cursor.fetchone())
+
 
 if __name__ == '__main__':
     unittest.main()