diff --git a/modal/functions.py b/modal/functions.py
index 9a00e635b..b6069c255 100644
--- a/modal/functions.py
+++ b/modal/functions.py
@@ -107,7 +107,14 @@ def __init__(self, stub: api_grpc.ModalClientStub, function_call_id: str, client
         self.function_call_id = function_call_id  # TODO: remove and use only input_id
 
     @staticmethod
-    async def create(function: "_Function", args, kwargs, *, client: _Client) -> "_Invocation":
+    async def create(
+        function: "_Function",
+        args,
+        kwargs,
+        *,
+        client: _Client,
+        function_call_invocation_type: "api_pb2.FunctionCallInvocationType.ValueType",
+    ) -> "_Invocation":
         assert client.stub
         function_id = function._invocation_function_id()
         item = await _create_input(args, kwargs, client, method_name=function._use_method_name)
@@ -117,6 +124,7 @@ async def create(function: "_Function", args, kwargs, *, client: _Client) -> "_I
             parent_input_id=current_input_id() or "",
             function_call_type=api_pb2.FUNCTION_CALL_TYPE_UNARY,
             pipelined_inputs=[item],
+            function_call_invocation_type=function_call_invocation_type,
         )
         response = await retry_transient_errors(client.stub.FunctionMap, request)
         function_call_id = response.function_call_id
@@ -1185,7 +1193,13 @@ async def _map(
             yield item
 
     async def _call_function(self, args, kwargs) -> R:
-        invocation = await _Invocation.create(self, args, kwargs, client=self._client)
+        invocation = await _Invocation.create(
+            self,
+            args,
+            kwargs,
+            client=self._client,
+            function_call_invocation_type=api_pb2.FUNCTION_CALL_INVOCATION_TYPE_SYNC_LEGACY,
+        )
         try:
             return await invocation.run_function()
         except asyncio.CancelledError:
@@ -1196,19 +1210,37 @@ async def _call_function(self, args, kwargs) -> R:
             return  # type: ignore
 
     async def _call_function_nowait(self, args, kwargs) -> _Invocation:
-        return await _Invocation.create(self, args, kwargs, client=self._client)
+        return await _Invocation.create(
+            self,
+            args,
+            kwargs,
+            client=self._client,
+            function_call_invocation_type=api_pb2.FUNCTION_CALL_INVOCATION_TYPE_ASYNC_LEGACY,
+        )
 
     @warn_if_generator_is_not_consumed()
     @live_method_gen
     @synchronizer.no_input_translation
     async def _call_generator(self, args, kwargs):
-        invocation = await _Invocation.create(self, args, kwargs, client=self._client)
+        invocation = await _Invocation.create(
+            self,
+            args,
+            kwargs,
+            client=self._client,
+            function_call_invocation_type=api_pb2.FUNCTION_CALL_INVOCATION_TYPE_SYNC_LEGACY,
+        )
         async for res in invocation.run_generator():
             yield res
 
     @synchronizer.no_io_translation
     async def _call_generator_nowait(self, args, kwargs):
-        return await _Invocation.create(self, args, kwargs, client=self._client)
+        return await _Invocation.create(
+            self,
+            args,
+            kwargs,
+            client=self._client,
+            function_call_invocation_type=api_pb2.FUNCTION_CALL_INVOCATION_TYPE_ASYNC_LEGACY,
+        )
 
     @synchronizer.no_io_translation
     @live_method
diff --git a/modal_proto/api.proto b/modal_proto/api.proto
index fef96710e..2cc536bcf 100644
--- a/modal_proto/api.proto
+++ b/modal_proto/api.proto
@@ -118,6 +118,12 @@ enum FileDescriptor {
   FILE_DESCRIPTOR_INFO = 3;
 }
 
+enum FunctionCallInvocationType {
+  FUNCTION_CALL_INVOCATION_TYPE_UNSPECIFIED = 0;
+  FUNCTION_CALL_INVOCATION_TYPE_SYNC_LEGACY = 1;
+  FUNCTION_CALL_INVOCATION_TYPE_ASYNC_LEGACY = 2;
+}
+
 enum FunctionCallType {
   FUNCTION_CALL_TYPE_UNSPECIFIED = 0;
   FUNCTION_CALL_TYPE_UNARY = 1;
@@ -1259,6 +1265,7 @@ message FunctionMapRequest {
   bool return_exceptions = 3;
   FunctionCallType function_call_type = 4;
   repeated FunctionPutInputsItem pipelined_inputs = 5;
+  FunctionCallInvocationType function_call_invocation_type = 6;
 }
 
 message FunctionMapResponse {