Tiger Woods and Justin Rose shared the lead on the back nine during the second round of the Tour Championship.
American duo Woods and Rickie Fowler, who will be Ryder Cup team-mates at Le Golf National next week, were out in front on five under after the first round at East Lake.
Woods, on the hunt for a first title in five years, birdied the second hole to take the outright lead on Friday and topped the leaderboard again on six under with a second gain at 12 following a first bogey just before the turn.
Fowler was six under through 11 holes in the final PGA Tour event of the season following bogeys at the first and 10th, with three birdies on the front nine enough to keep him firmly in the hunt for victory.
Rose is in pole position to win the FedEx Cup, the world number one sitting alongside Woods courtesy of third birdie of the day with a brilliant putt at the 13th.
Jon Rahm was joint-leader with Fowler after the Spaniard went out in 30 as a result of six birdies before the turn, but moved back to three under after losing his way on the back nine.
Bryson DeChambeau, the FedEx Cup standings leader when the tournament got under way, endured a nightmare second round of 75 to hand the initiative to Rose.
DeChambeau is way back on six over following a poor round which included seven dropped shots.
Rory McIlroy, Patrick Canley and Billy Horschel were two strokes off the leaders.