Steve Stricker matched the low round in major golf history, firing a seven-under par 63 on Thursday for a two-shot lead while Tiger Woods stumbled to a opening 77 at the 93rd PGA Championship.
And reigning US Open champion Rory McIlroy added to the drama, his status for round two unknown until Friday, after he strained a tendon in his right wrist hitting a shot on the third hole but playing through the pain and firing a 70.
Stricker, a 44-year-old American seeking his first major title, led a US charge atop the leaderboard in hopes of ending the record six-major drought since an American captured one of golf's most coveted crowns.
Perennial major contender Stricker had a chance to become the first man to fire a 62 in a major but missed a 10-foot birdie putt on the ninth hole, his last of the day.
"I realized it was for 62. I didn't realize it was for history," Stricker said. "It never really registered. I was just trying to make a birdie and never thought about the history of it. I hit a good putt. It just didn't go in."
American Jerry Kelly, a pal of fellow Wisconsinite Stricker, was second on 65 with compatriot Shaun Micheel another shot adrift and US veteran Scott Verplank fourth on 67.
No American has won a major title since Phil Mickelson at the 2010 Masters and if no US player hoists the Wanamaker Trophy on Sunday, 2011 will be the first year since 1994 with no US major winner.
Northern Ireland's McIlroy, who won his breakthrough major title two months ago at Congressional Country Club, suffered his injury after blasting a 7-iron shot near a tree root on the third hole.
Doctors made a preliminary diagnosis of the tendon strain after an MRI exam but McIlroy will not decide whether or not he plays Friday until he tests himself in warming up before his scheduled morning start.
"If I can strap it up and play again tomorrow I will," McIlroy said.
Former World No. 1 and 14-time major winner Woods, in his second week back after a three-month injury layoff, fired his worst opening round in a major, matching his sixth-worst career round to put him at risk of missing the cut.
It was the worst 18-holes for Woods at a US-based major and matched the second-worst of his career at any major event, the only poorer total being his 10-over 81 at the 2002 British Open.
"I can't just go out there and play by feel," Woods said. "I'm not at that point yet."
McIlroy felt pain and swelling in his wrist but fought on, admitting later, "To be honest, I finished with one hand."
"I jarred my right wrist and right arm," McIlroy said. "The impact went through the club. Just then, on that shot, there was a sharp pain up my arm."
McIlroy iced his forearm and had a medical trainer examine it amid fears he might have to withdraw, but he fired four birdies and four bogeys on the day.
"They said if you feel comfortable, play on, but there's no point in risking it," McIlroy said. "I thought, 'There are seven or eight months until the Masters so I might as well play through the pain.' I'm glad I did it."
Atlanta Athletic Club, renovated and lengthened after surrendering the lowest 72-hole major score of 265 to winner David Toms at the 2001 PGA Championship, showed its vulnerable side again thanks to Stricker.
Stricker opened with three birdies in a row and added others at the 260-yard par-3 15th and par-4 18th, dominating over the four-hole stretch most players declared the course's toughest.
"I really had no expectations coming into the round," Stricker said. "I didn't make many birdies in practice. I really didn't know what to expect but I got it going."
He added birdies at the first and par-5 fifth and nearly added another to make history, instead firing the 25th 63 in majors history, the first at a PGA since Woods in 2007 in the second round of his victory at Southern Hills.
Woods, who could miss the cut for only the third time in a major event, briefly grabbed a share of the lead after birdies on three of his first five holes following a 10th-tee start.
"I said, 'You know what, I'm feeling good, let's just let it go.' And it cost me the whole round," Woods said. "My shots don't shape like they used to."
Left leg injuries suffered in April at the Masters kept Woods from playing a full 18 holes competitively until last week.
Woods, chasing the all-time record of 18 majors won by Jack Nicklaus, has not won any title since his infamous sex scandal erupted in November of 2009 and has not won a major since the 2008 US Open.