diff --git a/python-package/xgboost/dask.py b/python-package/xgboost/dask.py
index 5fa37dedd..431a80d26 100644
--- a/python-package/xgboost/dask.py
+++ b/python-package/xgboost/dask.py
@@ -1606,8 +1606,9 @@ class DaskScikitLearnBase(XGBModel):
         should use `worker_client' instead of default client.
 
         """
-        asynchronous = getattr(self, "_asynchronous", False)
+
         if self._client is None:
+            asynchronous = getattr(self, "_asynchronous", False)
             try:
                 distributed.get_worker()
                 in_worker = True
@@ -1620,7 +1621,7 @@ class DaskScikitLearnBase(XGBModel):
                         return ret
                     return ret
 
-        return self.client.sync(func, **kwargs, asynchronous=asynchronous)
+        return self.client.sync(func, **kwargs, asynchronous=self.client.asynchronous)
 
 
 @xgboost_model_doc(
diff --git a/tests/python/test_with_dask.py b/tests/python/test_with_dask.py
index 343eff97b..f26097a83 100644
--- a/tests/python/test_with_dask.py
+++ b/tests/python/test_with_dask.py
@@ -705,8 +705,7 @@ async def run_from_dask_array_asyncio(scheduler_address: str) -> xgb.dask.TrainR
 async def run_dask_regressor_asyncio(scheduler_address: str) -> None:
     async with Client(scheduler_address, asynchronous=True) as client:
         X, y, _ = generate_array()
-        regressor = await xgb.dask.DaskXGBRegressor(verbosity=1,
-                                                    n_estimators=2)
+        regressor = await xgb.dask.DaskXGBRegressor(verbosity=1, n_estimators=2)
         regressor.set_params(tree_method='hist')
         regressor.client = client
         await regressor.fit(X, y, eval_set=[(X, y)])