Spain's second-ranked Jon Rahm fired a five-under par 65 to match world number one Dustin Johnson for the lead after Friday's opening round of the US PGA Tour Championship.
Rahm managed to find only three of 14 fairways at East Lake but reached 14 of 18 greens in regulation to equal Johnson at 13-under after 18 holes in a 30-man season-ending showdown in Atlanta for a $15 million playoff prize.
"I kind of survived the first six or seven holes, took it on the back nine and played a really solid round of golf," Rahm said.
"My driving could use a little improving. It was just a little bit of every which way. I was a little hesitant off the tee and that's what I'd like to change."
Johnson, who shot 67, began on 10-under by virtue of his season points lead. Rahm was next on 8-under with third-ranked American Justin Thomas on 7-under and other rivals starting up to 10 strokes adrift in the staggered start system.
"I'm pleased with the way I played," Johnson said. "It's a decent score. I need to keep doing what I'm doing and giving myself some looks."
Thomas, the 2017 playoff champion, had three birdies in his first four holes on the way to a 66 to stand third on 11-under, two strokes ahead of world number four Rory McIlroy, who shot 64 to leap into contention.
New dad McIlroy, who began seven behind Johnson, is chasing his third US PGA playoff crown in five seasons and still thinking of daughter Poppy.
"I was like, 'OK, there's a feeding coming up.' It's natural -- between shots you think of other things," McIlroy said.
"It's nice to have this little four or five hours to myself. I played really well, as good as I have in a long time and that was very encouraging."
Last-pair partners Rahm and Johnson continued their duel from last week's BMW Championship, when Johnson sank a long putt on the 72nd green to force extra holes and Rahm made a 66-footer for birdie to capture the playoff.
"It was fun playing out there with Jon," Johnson said. "Pretty solid."
Johnson sank a six-foot birdie putt at the second and dropped his approach inches from the cup at the par-5 sixth for a tap-in birdie to reach 12-under. But he made bogey at the eighth and par-3 ninth after missing the fairway and 10-foot par putts.
"Need to hit it a little straighter," Johnson said. "I didn't hit enough fairways... if you hit it in the fairways, there's not a hole you can't get after."
Rahm made a 19-foot birdie putt at the second, took bogey at three, then dropped his approach inches from the cup to set up a birdie at six.
"It was hard the first four or five holes, not uncomfortable but just doubtful of the dynamics of everything," Rahm said. "After that I was a little bit more comfortable."
Johnson and Rahm each birdied the 12th, 13th and par-3 15th, the world's top-ranked players bringing out the best in each other.
After Rahm made a 29-foot birdie putt at 12, Johnson followed him from 27 feet. At 13, Rahm sank a 12-footer for birdie and Johnson topped him from 10 feet.
On the par-3 15th, Rahm sank a 23-foot birdie putt and Johnson made a 16-footer behind him.
Rahm, followed with a 16-foot birdie putt at 16 after Johnson missed from 25 feet, leaving them both at 13-under.
"I putted as well as I ever have on Bermuda greens in my life," Rahm said.
At the par-5 18th, Johnson blasted out of a greenside bunker to 4 1/2 feet but lipped out on his birdie putt while Rahm lipped out on his bunker bid for birdie and settled for a tap-in par.
- Rory's 'sanctuary' -
Four-time major winner McIlroy, who celebrated Poppy's birth Monday, went four days without touching a club.
"Golf was he furthest thing from my mind the first few days this week," said McIlroy. "That meant I could come here and somewhat focus on what I'm supposed to do."
Golf provided McIlroy an escape into his usual challenges.
"It's sort of a sanctuary," he said. "Great start. I played some nice golf."
McIlroy has not managed a top-10 finish since the US PGA Tour returned from a three-month COVID-19 shutdown in June, impending fatherhood and spectator-less events taking a toll.
"It was a perfect storm," he said. "I've seen signs my game is getting better. I was coming in with no expectations... I'm happy to start the way I have."