diff --git a/fastapi/dependencies/utils.py b/fastapi/dependencies/utils.py
index 14ec7f4d1..4021f212c 100644
--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -600,11 +600,14 @@ async def solve_dependencies(
         else:
             stack = request.scope.get("fastapi_astack")
             assert isinstance(stack, AsyncExitStack)
-            called = run_in_threadpool(call, **sub_values)
+            called = await run_in_threadpool(call, **sub_values)
             if hasattr(called, "__aenter__"):
                 solved = await stack.enter_async_context(called)
+            elif hasattr(called, "__enter__"):
+                cm = contextmanager_in_threadpool(called)
+                solved = await stack.enter_async_context(cm)
             else:
-                solved = await called
+                solved = called
         if sub_dependant.name is not None:
             values[sub_dependant.name] = solved
         if sub_dependant.cache_key not in dependency_cache: