World number one Brooks Koepka birdied the 18th hole Friday, capping a three-under-par 67 to take a one-shot lead over Justin Thomas and Rory McIlroy in the US PGA Tour Championship.
Koepka posted his second straight 67 at East Lake in Atlanta, Georgia.
Under the "staggered start" format by which players were spotted strokes based on their position in the playoff standings, that put him on 13-under par -- one stroke in front of American Thomas and Northern Ireland star McIlroy.
McIlroy capped his 67 with back-to-back birdies, including a bravura finish at 18 where he was in the trees off the tee.
Thomas -- who went into the tournament as the top seed, awarded a two-stroke edge after his win in the BMW Championship -- was alone atop the leaderboard at 13- under through 16 holes but slipped back with a bogey at 17 and finished with a two-under 68.
Koepka who started the week three shots off the lead, couldn't get his eight-foot eagle putt to drop at the last, but he tapped in for his fourth birdie of the day.
"I feel good," Koepka said. "Obviously the game's kind of coming into form there. It's been a struggle the last few weeks.
"I found some stuff and I'm very pleased with where I'm at," said Koepka, who had three straight birdies at the sixth, seventh and eighth, but like most on the day found the going tougher on the back nine when he returned after a weather delay.
Thomas also had three front-nine birdies, but he was one-over on the back and admitted he "kind of had a hard time getting back into it" after the delay.
"But if I continue to drive it like I did today, I feel like I can really do some damage this weekend," Thomas said. "I just have to realize that I played really well today."
American Xander Schauffele was alone in fourth, his eagle at 18 giving him a 69 that put him two shots off the lead.