(Reuters) - Brooks Koepka earned a one-shot lead over Rory McIlroy and Xander Schauffele after the third round at the Tour Championship on Sunday, setting up the prospect of a mouth-watering finale to the PGA Tour season in the race for the $15 million first prize.
A deft chip at the par-five 18th led to a tap-in birdie and a two-under-par 68 for Koepka at East Lake in Atlanta.
At 15 under par, Koepka will begin the final round on Sunday afternoon with the narrowest of leads over fellow American Schauffele (67) and Northern Irishman McIlroy (68).
Englishman Paul Casey (68) and American Justin Thomas (71) trail by four shots, with Thomas having been left reeling by a triple-bogey at the 16th hole.
The third round was completed on Sunday morning after being suspended on Saturday afternoon due to a thunderstorm.
Six spectators were subsequently injured after a lightning bolt struck a tree on the course.
Five were taken to hospital and all have now been released, the PGA Tour said in a statement.
Koepka, who had completed five holes on Saturday, acknowledged that he was assisted by the delay.
"It did help," he told Golf Channel. "I was struggling to find some rhythm.
"Old habits crept in a little bit and it was nice to take a little break."
World number one Koepka said he would not be fazed by the pressure of playing for $15 million.
"It's easy for me -- just go play golf," he said of his attitude. "I guess that's what I was born to do."
Koepka and McIlroy, both four-times major champions, will be paired again, four weeks after locking horns at the WGC-St. Jude Invitational, where Koepka demolished his rival.
McIlroy said it was not particularly important to be in the final pairing, though he still relished the challenge.
"I've been trying not to look at the leaderboards at all this week because it really doesn't matter what anyone else is doing," he said.
He also observed that it had been important to adapt quickly to the significantly cooler conditions on Sunday.
"I think this is the first time ever I've played East Lake and haven't been sweating.
"The ball's not traveling quite as far. Because of the cold air the ball's getting hit by the wind a little more."
Schauffele, meanwhile, had his first ever hole-in-one, from 240 yards no less, at the par-three ninth, where his ball landed on the front of the green and trickled into the cup at perfect pace.
"I told my caddie I think (the first ace) will come in a tournament round and be in a hole longer than 230 (yards). I guess it came true," said the 2017 Tour Championship winner.
"I didn't even see it go in. I looked away. I did pull it too. I'm not going to lie. I yanked it."
(Reporting by Andrew Both in Cary, North Carolina; Editing by Brian Homewood and Ian Chadband)