Shootout in St Louis
  Tiger Woods on the sixth hole during the second round of the 100th PGA Championship held at Bellerive Golf Club on August 10, 2018 in St. Louis, Missouri. (Photo by Montana Pritchard/PGA of America)

 Tiger Woods on the sixth hole during the second round of the 100th PGA Championship held at Bellerive Golf Club on August 10, 2018 in St. Louis, Missouri. (Photo by Montana Pritchard/PGA of America)

Candles and a telegram are the order of the day for any 100th birthday celebration, but the centennial US PGA turned into a spectacular fireworks display as the world's best players took Bellerive Country Club to its knees.

Overnight leader Gary Woodland blasted a 66 to lead by a shot in the clubhouse on 10-under par from Kevin Kisner, who needed a birdie at his final hole for a 62 to match the lowest round in major history but bogeyed the ninth instead to post a 64.

Astonishingly, those weren't even the lowest rounds on a morning of red-hot scoring in 90-degree temperatures in St Louis.

Two-time US Open champion Brooks Koepka and former Masters champion Charl Schwartzel both gave themselves putts for eight under 62s but had to settle for becoming the 15th and 16th men to shoot 63 in the season's final major.

Koepka came closest to matching the 62 shot by Branden Grace at Royal Birkdale last year, lipping out from 20 feet at the ninth before tapping in for an immaculate, seven-under round that left him just two shots off the pace on eight under.

"I wasn't really thinking about that [the record] on the putt — I've been so in the zone you don't know where you are or where you're at," Koepka said.

"But right when we walked off, my caddie [Portrush's Rickie Elliott] said, 'Man, you could have had 62 there to equal the major championship record, which would have been nice.

"It looked good the whole way, and I thought it was in, but it didn't drop."

With back to back US Opens under his belt, Koepka is gunning for a Harrington-esque third major victory in two years despite missing this year's Masters during his four-month layoff nursing a wrist injury.

"It would be special," Koepka said. "Any time you can win two Majors in a year, that's pretty unique, pretty special.

"And especially where I started the season, missing the Masters and only being able to play three this year is quite disappointing, but trying to make the most of it."

As for South African Schwartzel, he made eight birdies and a bogey in his first 16 holes, but he couldn't take advantage of the par-five 17th and then left a 40 footer well short at the 18th.

Ironically, it was one of the few putts the South African failed to get to the hole all day.

"I switched putters, went to a little heavier putter, and at least got the ball to the hole and made a few putts," said Schwartzel, who believes the birdie-fest will continue all weekend.

"In most Majors, the weekends get difficult, but I think this course you're going to have to keep shooting birdies."

He was tied with Belgium's Thomas Pieters and world No 1 Dustin Johnson on seven-under, just three behind Kansas native Woodland.

Johnson was one over for his round with just eight holes to go but soon caught fire, making five birdies in six holes from third, where an errant tee shot from Spaniard Jorge Campillo at the driveable 11th, landed next to him as he made contact and turned around to glare as his ball soared towards the green.

"I feel like I'm starting to roll the putter really well, seeing the lines good," Johnson said after his 66. "And I'm definitely swinging well.

"I'm definitely wanting to get that second Major. I'm in a good position going into the weekend, I'm going to have to play a good 36 holes though if I want to have a chance to win."

Woodland made four birdies and an eagle three at the 17th, his eighth, to followed his opening 64 with a 66 for the early lead on 10-under.

"For me, I'm very happy with where I'm at," he said, crediting a move to putting coach Phil Kenyon at the Open for his renewed confidence on the greens. "I'm very comfortable with how I'm driving the golf ball. 

"The iron game, the distance control this week has been phenomenal. And when I stand over a golf ball putting as comfortable as I am right now, I'm pretty excited."

Seven of the last nine US PGA champions were first-time major winners and while Woodland would fit the bill, so too would Kisner (34), who has twice come close over the last 12 months.

A year ago, he led going into final round at Quail Hollow but shot 74 and tied for seventh behind Justin Thomas.

Just three weeks ago at The Open, he held a share of the 54-hole lead but again closed with a three-over 74 to finish tied for second behind Francesco Molinari.

Yesterday, he looked to be heading for a possible 62 or 61 when he played the back nine in six-under 29, picking up birdies at the 10th, 11th, 13th, 15th, 17th and 18th.

"Kept throwing darts on the back nine and holing the eight, 10-footers I need to, to make the birdies," he said.

Sadly, he couldn't keep it going, and while he birdied the seventh to give himself a chance of a 61, he could only par the par-five eighth and then bogeyed the ninth.

Can he win?

"I don't know, y'all ask me that question every time," Kisner said. "All I know is if I hit it in the fairway and hit it on the green and make the putt I'm probably going to have a good shot at it."