diff --git a/litellm/proxy/proxy_server.py b/litellm/proxy/proxy_server.py
index 0ae498baa..210912fcf 100644
--- a/litellm/proxy/proxy_server.py
+++ b/litellm/proxy/proxy_server.py
@@ -3673,8 +3673,9 @@ async def chat_completion(
         # skip router if user passed their key
         if "api_key" in data:
             tasks.append(litellm.acompletion(**data))
-        elif isinstance(data["model"], list) and llm_router is not None:
-            _models = data.pop("model")
+        elif "," in data["model"] and llm_router is not None:
+            _models_csv_string = data.pop("model")
+            _models = _models_csv_string.split(",")
             tasks.append(llm_router.abatch_completion(models=_models, **data))
         elif "user_config" in data:
             # initialize a new router instance. make request using this Router
diff --git a/tests/test_openai_endpoints.py b/tests/test_openai_endpoints.py
index 7bc97ca59..43dcae3cd 100644
--- a/tests/test_openai_endpoints.py
+++ b/tests/test_openai_endpoints.py
@@ -424,10 +424,7 @@ async def test_batch_chat_completions():
         response = await chat_completion(
             session=session,
             key="sk-1234",
-            model=[
-                "gpt-3.5-turbo",
-                "fake-openai-endpoint",
-            ],
+            model="gpt-3.5-turbo,fake-openai-endpoint",
         )
 
         print(f"response: {response}")