diff --git a/src/backend/core/services/lobby.py b/src/backend/core/services/lobby.py
index bce85eae..55fab912 100644
--- a/src/backend/core/services/lobby.py
+++ b/src/backend/core/services/lobby.py
@@ -342,3 +342,9 @@ class LobbyService:
             return
 
         cache.delete_many(keys)
+
+    def clear_participant_cache(self, room_id: UUID, participant_id: str) -> None:
+        """Clear a given participant entry from the cache for a specific room."""
+
+        cache_key = self._get_cache_key(room_id, participant_id)
+        cache.delete(cache_key)
diff --git a/src/backend/core/tests/services/test_lobby.py b/src/backend/core/tests/services/test_lobby.py
index 600d3220..43f745de 100644
--- a/src/backend/core/tests/services/test_lobby.py
+++ b/src/backend/core/tests/services/test_lobby.py
@@ -839,3 +839,35 @@ def test_clear_room_empty(settings, lobby_service):
     assert cache.keys(f"test-lobby_{room_id!s}_*") == []
     lobby_service.clear_room_cache(room_id)
     assert cache.keys(f"test-lobby_{room_id!s}_*") == []
+
+
+def test_clear_participant_cache(lobby_service):
+    """Test clearing a specific participant entry from cache."""
+    room_id = uuid.uuid4()
+    participant_id = "test-participant-id"
+
+    cache_key = f"{settings.LOBBY_KEY_PREFIX}_{room_id!s}_{participant_id}"
+    participant_data = {
+        "status": "waiting",
+        "username": "test-username",
+        "id": participant_id,
+        "color": "#123456",
+    }
+    cache.set(cache_key, participant_data, timeout=settings.LOBBY_WAITING_TIMEOUT)
+    assert cache.get(cache_key) is not None
+
+    lobby_service.clear_participant_cache(room_id, participant_id)
+    assert cache.get(cache_key) is None
+
+
+def test_clear_participant_cache_nonexistent(lobby_service):
+    """Test clearing a participant that doesn't exist in cache."""
+    room_id = uuid.uuid4()
+    participant_id = "nonexistent-participant"
+
+    cache_key = f"{settings.LOBBY_KEY_PREFIX}_{room_id!s}_{participant_id}"
+    assert cache.get(cache_key) is None
+
+    lobby_service.clear_participant_cache(room_id, participant_id)
+
+    assert cache.get(cache_key) is None