PONTE VEDRA BEACH, May 9, 2014 (AFP) - Kaymer, who began on the 10th tee, fired the lowest nine-hole score in Players history, a seven-under 29 on the front side at TPC Sawgrass.
"Today was a very special round," Kaymer said. "I didn't make many mistakes."
Kaymer's 63 matched Fred Couples in 1992, Greg Norman in 1994 and Roberto Castro last year for the lowest round in the tournament's 40-year history.
That moved Kaymer, the 2010 PGA Championship winner, two strokes clear of American Russell Henley with South Korean Bae sang-Moon three shots adrift in third at the $10 million event.
A pack in fourth on 67 included reigning US Open champion Justin Rose, fellow Englishman Lee Westwood, Spaniards Sergio Garcia and Gonzalo Fernandez-Castano and Americans Brian Stuard, Jordan Spieth, Gary Woodland and Scott Stallings.
Kaymer made short birdie putts at the par-5 11th and par-4 15th, but sizzled after the turn, starting with a 26-foot birdie putt at the first.
Kaymer reached the green at the par-5 second in two and tapped in for birdie, then added a 14-foot birdie at the fourth before closing with four birdies in a row.
The stellar final run included a 17-foot putt at the par-3 eighth and a tap-in birdie at the par-5 ninth after blasting out of a bunker just 20 inches from the cup.
Henley, who missed the cut last year in his Players debut, fired a back-nine 30 that matched the low back-nine mark, with no putt longer than 16 feet.
"I knew I was playing well and felt really comfortable on the greens," Henley said. "As long as I keep feeling comfortable with the putter, I think I can putt well on these greens."
Henley opened with three birdies in the first four holes but suffered his lone stumble of the day at the par-4 seventh when his tee shot found the water on his way to a double bogey.
Henley answered by opening the back nine with three birdies in a row and running off three more in a row from the 15th through 17th holes.
Henley, 25, seeks his third PGA title, having won last year's Sony Open in Hawaii in his first start as a PGA Tour member and taken a four-way playoff to win the Honda Classic in March.
- Scott stumbles to 77 -
Four players in the field are able to dethrone Tiger Woods from atop the world rankings this week but after the first 18 holes none of them were in the position they needed to do so.
Aussie Adam Scott, who needs a top-16 showing, found water off the tee at 17 and 18 and finished with back-to-back double bogeys for a 77 to share 133rd place.
Sweden's Henrik Stenson, who must finish in the top six, opened on 71 to share 48th.
American Matt Kuchar, who must win to have a chance, began and ended the back nine with double bogeys to also stand on 71.
American Bubba Watson, in his first event since winning his second Masters title last month, opened on 69 to share 19th. He needs to finish second alone for a chance at number one Monday.
Rose, preparing to defend the major title he won last year at Merion next month at Pinehurst, had an "awful" warm-up session but shined on the course.
"One of those weird days in the game of golf," Rose said. "Had not much feel of anything that I was doing to be honest with you and having played quite well recently, it was a bit of an out-of-the-blue moment.
"Sometimes it lowers your expectation."
Garcia, who shared the Sunday lead with Woods at the 17th tee last year only to plunk two shots into the water and take a quadruple bogey, made the island green on his first try this time and made par.
"It did cross my mind," Garcia said. "It's a new year. I was able to do much better there."
Reigning British Open champion Phil Mickelson soared to a 75, the lefty saying, "it's a little disappointing and frustrating... it's just not quite clicking right now."
Scores on Thursday after the first round of the $10 million US PGA Players Championship (par 72, USA unless noted):
63 - Martin Kaymer (GER)
65 - Russell Henley
66 - Bae Sang-Moon (KOR)
67 - Lee Westwood (ENG), Brian Stuard, Gonzalo Fernandez-Castano (ESP), Gary Woodland, Jordan Spieth, Scott Stallings, Justin Rose (ENG), Sergio Garcia (ESP)
68 - Scott Brown, Ernie Els (RSA), Dustin Johnson, Pat Perez, Justin Leonard, Bill Haas, Joost Luiten (NED)
69 - Brendon de Jonge (ZIM), Geoff Ogilvy (AUS), Kevin Streelman, Jason Dufner, Zach Johnson, Graeme McDowell (NIR), Brendan Steele, Graham DeLaet (CAN), John Huh, Bubba Watson