Jason Dufner grabbed a two-shot lead at the PGA Chamoionship with a stunning 63 at rain-softened Oak Hill, but perfect conditions Saturday were set to offer a much more formidable test.
Warm and dry conditions with a light breeze greeted players for the start of the third round, giving teeth to a course where receptive greens allowed players to attack the pins.
"Guys that are able to close these majors off can adjust to the conditions," Dufner said. "If the greens speed up I'll have to adjust just like everybody in the field.
"It will be another tough day, a good test."
Dufner matched the lowest score in major championship history with five birdies and an eagle to finish 36 holes at nine under par 131, but came up short on a 12-foot birdie putt at the 18th that would have given him an unprecedented 62.
That brought back memories of Dufner's collapse at the 2011 PGA Championship, when he led by four strokes with four holes to play only to fall into a playoff and lose to Keegan Bradley.
So there was plenty of hope for the other contenders, including Masters champion Adam Scott of Australia and Americans Jim Furyk and Matt Kuchar on 133 and US Open winner Justin Rose of England and British Open runner-up Henrik Stenson of Sweden on 134.
"The course will show its teeth at some point," Rose said. "The greens will get firm and fast, especially by Sunday, and Oak Hill will always need to be respected."
Scott, however, was counting on the rain-soaked course to remain vulnerable.
"I think it's not going to dry out at all to where it will get really tough," Scott said. "The greens are going to be fairly moist for the whole weekend, and even the fairways probably, so it's going to be right there for the taking at the weekend, although it's still going to penalize bad shots."
World number one Tiger Woods went to the practice range Friday night for an emergency session with swing coach Sean Foley after struggling to a second-round 70 that left him on 141 -- 10 strokes behind Dufner.
With 49 rivals equal with or above him, Woods was going to have to make his greatest comeback to have any hope at a 15th major title this week.
"I'm going to have to do my job and shoot a good round," Woods said. "I've got to go out there and post something in the mid to low 60s. It definitely can be done."
The largest deficit Woods has overcome in the last 36 holes to win a major was six shots at the 2005 Masters and he has never won a major when not leading after 54 holes.
The best victory rally for Woods over 36 holes was when he came from nine shots behind to win in 1999 in the first of his eight triumphs at Torrey Pines, where he won his most recent major title at the 2008 US Open.
"I'm so far back that if the leaders go ahead and run off with it and shoot a low number, I'm going to be pretty far behind," Woods said.