St. Louis - Two-time US Open champion Brooks Koepka and 2011 Masters champion Charl Schwartzel flirted with matching the lowest round in major golf history but fell short on Friday to leave Gary Woodland in the lead at the 100th PGA Championship.

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Woodland fired a four-under par 66 to stand on 10-under 130 after 36 holes to finish one stroke ahead of playing partner Kevin Kisner with Koepka two adrift at Bellerive Country Club.

Tiger Woods, who birdied the second and third holes after an opening par, joined Rory McIlroy and defending champion Justin Thomas in the top afternoon group on a course offering near-record scores.

"I feel safe where my game is. I'm not too worried with what anyone else is doing out there," Woodland said. "The golf course is gettable. So we'll see some putts go in."

Americans Koepka and Kisner and South African Schwartzel excited the crowd early by chasing the all-time record low men's major score of 62 set by South African Branden Grace in the third round at the 2017 Open at par-70 Royal Birkdale.

Koepka, who started on the back nine, birdied the par-5 eighth and had a 20-foot birdie putt at the ninth for 62 but rolled it three feet past and made the comeback to shoot 63.

"I didn't know," Koepka said. "I was just trying to make the thing. I thought I had made it. Sometimes you are in your own mind and don't know where you are at."

Kisner, who also began off the 10th tee, made a six-foot birdie putt at the seventh to reach 7-under but found a bunker at the par-5 eighth and parred then at nine chipped 23 feet past the hole then two-putted for bogey and a 64.

"I'm all right with it," Kisner said. "I knew I was playing well and had made a few birdies. I like my position going into the weekend."

Kisner birdied six of the first nine holes but opened his second nine with six pars.

"Couldn't have asked for a better start. I was throwing darts at it," Kisner said. "I hit it well on the second nine. I just didn't make any putts."

Woodland eagled the par-5 17th, dropping his second shot five feet from the cup and holing the putt, then birdied the second and third and answered a bogey stumble at four with a 25-foot birdie putt at the eighth - all as Kisner watched.

"He's rolling the rock and really striping it," Kisner said. "We're going to have a pretty good battle if I can keep up with him."

Woodland has never finished better than 12th in 27 major starts but he has never started so well in one either.

"I'm very happy with where I'm at," he said. "When I stand over a golf ball putting as comfortable as I am right now, I'm pretty excited."

Koepka defended his US Open crown in June, the first back-to-back US Open winner since Curtis Strange in 1988-89.

Kisner, whose two PGA wins came in 2015, shared seventh in last year's PGA, his best major finish until last month.

Schwartzel, the 2011 Masters winner, didn't threaten the lead with his run at 62 but sank a seven-foot birdie putt at the par-3 16th to reach 7-under. He found a fairway bunker and parred the par-5 17th then left a 49-foot birdie putt five feet short at the 18th.

On the prospect of a 62 he said: "I didn't know there was that. I would have liked that."

Schwartzel, who matched the tournament record with a 63, was on 133 with world No 1 Dustin Johnson and Belgium's Thomas Pieters. South African Brandon Stone was seventh on 134.

Three-time major winner Jordan Spieth, ranked eighth, can complete a career Grand Slam with a victory this week. But the 25-year-old American shot 67 to stand on 137.

Woods, a 14-time major champion in his comeback season after spinal fusion surgery, and McIlroy grinded to 70s in round one before huge crowds.