Stanley ran off four straight birdies on the front nine, and then added two more late in his round on a steamy Thursday afternoon at East Lake for a 6-under 64. He had a two-shot lead.
Spieth had a 67, which was just fine with him. No one among the top five seeds in the FedEx Cup had a lower score, so that kept Spieth on track in his bid to join Tiger Woods as the only two-time winner of the $10 million bonus.
Stanley is the No. 22 seed. He needs to win and have Spieth finish toward the bottom third of the 30-man field to claim the FedEx Cup.