diff --git a/vllm/v1/worker/gpu_model_runner.py b/vllm/v1/worker/gpu_model_runner.py
index f83ed8a8ac4a..7901adb3be9d 100644
--- a/vllm/v1/worker/gpu_model_runner.py
+++ b/vllm/v1/worker/gpu_model_runner.py
@@ -713,11 +713,14 @@ def __init__(
         # Separate cuda stream for overlapping transfer of sampled token ids from
         # GPU to CPU when async scheduling is enabled.
         self.async_output_copy_stream: torch.cuda.Stream | None = None
-        # cuda event to synchronize use of reused CPU tensors between steps
-        # when async scheduling is enabled.
-        self.prepare_inputs_event: torch.Event | None = None
         if self.use_async_scheduling:
             self.async_output_copy_stream = torch.cuda.Stream()
+        # cuda event to synchronize use of reused CPU tensors between steps
+        # whenever steps overlap (async scheduling, or the PP batch queue):
+        # input prep for step N+1 runs while step N's non_blocking H2D copies
+        # from the same pinned buffers may still be pending.
+        self.prepare_inputs_event: torch.Event | None = None
+        if self.vllm_config.max_concurrent_batches > 1:
             self.prepare_inputs_event = torch.Event()
 
         # self.cudagraph_batch_sizes sorts in ascending order.