Rochester-World number one Tiger Woods was set to make an early charge as the 95th PGA Championship opened on Thursday after a pre-dawn thunderstorm dampened Oak Hill.
Overnight showers softened the 7,163-yard, par-70 layout but skies were clear as a field of 156 players began their first rounds at the final major tournament of the year.
Woods, a 14-time major winner chasing the record 18 victories by Jack Nicklaus, has not won one since the 2008 US Open but comes into the event on top form after collecting his fifth title of the year last week.
Woods won the World Golf Championships Bridgestone Invitational by seven strokes for his eighth career triumph at Firestone, a run that included a second-round 61 to match the lowest round of his career.
But Woods shared 39th at the 2003 OGA at Oak Hill, his second-worst 72-hole major result as a professional, and he has yet to show his once-dominating form for four rounds at a major this year, settling for a share of fourth at the Masters and sixth at last month's British Open.
"The key is to keep giving myself chances and eventually I'll start getting them," Woods said.
Woods, who seeks his 80th career title to pull within two of Sam Snead's all-time US PGA Tour record win total, was set to start at 14:35 off the 10th tee alongside fellow Americans Davis Love and Keegan Bradley in a group of past PGA Championship winners.
Other early starters, also off the back nine first, included Japan's Hideki Matsuyama, Swede Henrik Stenson, South Africans Ernie Els and Charl Schwartzel, South Korean Yang Yong-Eun, Ireland's Padraig Harrington and Northern Ireland's Graeme McDowell.
The feature pairings of the year's first three major winners - Masters champion Adam Scott of Australia, US Open champion Justin Rose of England and British Open winner Phil Mickelson of the United States - was set to start off the first tee at 15:45.
Two groups ahead of them will be defending champion Rory McIlroy of Northern Ireland, who has struggled this season following an equipment change and a slow start to the season.
"I got into a couple of bad habits with my swing and it has just taken a little bit longer to get out of them," McIlroy said. "Every time you don't play well it chips away at your confidence and it's just about building that back up."
McIlroy plays alongside Germany's Martin Kaymer and Fiji's Vijay Singh, also past PGA winners.
Other contenders with afternoon tee times include Aussie Jason Day, England's Lee Westwood and Luke Donald, South African Tim Clark and American Bubba Watson.
Oak Hill promised a demanding test with tricky greens, dense rough and tight, tree-lined fairways, but graduated rough and fairness in layout had players praising the course.
"The course is in incredible shape. It's one of the best setups I've ever seen," Mickelson said. "If you play well you can make birdies and if you play poorly you are going to be severely penalized with thick rough."