Brooks Koepka and Charl Schwartzel equalled the lowest score in tournament history as the 100th US PGA Championship turned into a shootout in St Louis.
Koepka's flawless 63 left the double US Open champion two shots off the clubhouse lead held by fellow American Gary Woodland, whose 10-under-par halfway total of 130 established a championship record.
Woodland enjoyed a one-shot lead over compatriot Kevin Kisner, who bogeyed the last to shoot 64, with Schwartzel three off the lead alongside world number one Dustin Johnson and Thomas Pieters after eight birdies and a bogey in his 63.
A birdie on the last would have seen Koepka or Schwartzel equal Branden Grace's major record of 62, set during the third round of the Open Championship at Royal Birkdale last year.
But while Schwartzel did not come close from long range, Koepka's attempt from 20 feet agonisingly caught the edge of the hole and stayed out.
"I just was trying to make the thing and I really thought I made it," said Koepka, who successfully defended his US Open title at Shinnecock Hills in June. "I didn't even think of it [the 62]. I've been so in the zone you don't know where you are or where you're at."
Kisner had also had the opportunity to shoot 62 after covering the back nine in 29 and picking up another birdie on the seventh, only to bogey the ninth, his final hole of the day.
Woodland is yet to record a top 10 in 27 major appearances but has reaped the rewards of working with two British coaches, Phil Kenyon on his putting and Pete Cowen on his short game.
"For me as a whole, the putting was kind of just the last piece of the puzzle," said the 34-year-old from Kansas, who admits he is in "enemy territory" in neighbouring Missouri, after a 66.
"Butch [Harmon] and I focused so hard this year on driving the golf ball because, when I drive it in play, I'm playing a game a lot of guys aren't playing out here, and that's a huge advantage. Once that started to come around, really the putting was the last piece.
"When I see putts go in, I'm a completely different player, especially with as aggressive as I'm playing right now. So it was nice to get some work in with Phil at the Open, and then I've had a couple weeks to work on it."
Kenyon also works with Open champion Francesco Molinari, who is five shots off the lead after a 67, with world number three Justin Rose another stroke back following a 69.
"I'm happy with the way I scored considering how I played," said Rose, who did not play a practice round after recent back spasms. "I played poorly today, really struggled, didn't hit my irons well at all."
The low scoring meant Tiger Woods and Rory McIlroy began their second rounds 10 shots off the lead and they completed just seven holes before play was suspended due to the threat of lightning.
McIlroy had opened with seven pars but Woods had birdied the second, third and fifth to improve to three under. After a delay, officials confirmed that play had been abandoned for the day.
- Play resumes at 0700 local time on Saturday