ST.. LOUIS - Brooks Koepka fired a 4-under-par 66 on Saturday, Aug. 11, to assume a two-shot lead after the third round of the 100th PGA Championship, the final major tournament of the 2018 PGA Tour season, being contested at venerable Bellerive Country Club just outside St. Louis.

Koepka, the reigning winner of back-to-back U.S. Open Championships, is at 12 under for the weekend and is in the driver's seat for his third victory in the past seven major championships. He swooped to the lead on the front nine and then stumbled a bit with a pair of bogeys before recording a final birdie on the par-5 17th.

Adam Scott of Australia, the 2013 Masters winner, is two strokes back after a round-best 65 on Saturday. Gary Woodland (who shot a 71), Jon Rahm of Spain (66) and Rickie Fowler (69) are tied for third at 9 under, three strokes off Koepka's lead.

Four-time PGA Championship winner Tiger Woods shot a 66 on Saturday and heads to the final round at 8 under, four off the lead, tied for sixth place with 2009 Open Championship winner Stewart Cink (who also carded a 66), 2015 PGA Championship winner Jason Day of Australia (67), defending PGA Championship winner Justin Thomas (68) and Shane Lowry of Ireland (69).

Julian Suri (68), reigning Open Championship winner Francesco Molinari of Italy (68) and Kevin Kisner (72) are tied for 12th at 7 under. Fourteen players are within five stokes of the lead with the Wannamaker Trophy on the line Sunday.

Woods, whose earlier charge on the easier front nine raised the massive gallery's excitement to fever pitch, was among a logjam of six trailing by four shots.

He parred every hole on the back nine and his 66 matched his lowest round in a major this year, but he was a little disappointed, not least with a three-putt at the par-5 17th.

"It could have been a little bit closer but I've got a shot going into tomorrow," he said.

Earlier, Koepka brought Bellerive to its proverbial knees with five birdies in an outward half of 30 strokes.

And he made it look ever so easy, bludgeoning his drives massive distances and honing in on the pins with unerring accuracy.

He holed only one lengthy putt, the other four birdies coming from tap-in range, or close to it.

Koepka seemed an unlikely candidate to falter, but falter he did.

A bogey at the 14th, where he found a greenside bunker, ended a run of 43 holes without a dropped shot, and he promptly bogeyed the next too after his drive ended behind a tree, from where he took a penalty drop.

Those errors brought Woods back into contention.

Woodland began the third round, which was played at the conclusion of the second round Saturday morning because of a weather delay on Friday afternoon, with a one-shot lead over Kisner and a two-stroke advantage on Fowler and Koepka.

Rahm charged up the leaderboard and into a prime stalking position with a bogey-free 66 that included birdies on the 16th and 17th holes.

Woodland stayed within three strokes of Koepka despite an up-and-down round. He had two bogeys and a pair of birdies on the front nine and uncorked a triple bogey on the 10th before birdieing the 12th and 14th.

Woods missed makeable birdie putts on both the 17th and 18th that could have closed the gap Koepka had extended on the field. He is 10-under par for the front nine over the first three rounds and 2 over on the back nine through 54 holes.

World No. 1 Dustin Johnson, who started the third round tied for fifth, ballooned to a 72 and into a tie for 21st place after three bogeys and a double bogey through 16 holes on Saturday.