Rochester - Masters champion Adam Scott seized the second-round lead at the PGA Championship on Friday, but strong rounds by Justin Rose and Webb Simpson kept him from pulling away at rain-soaked Oak Hill.
The 33-year-old Australian birdied three of his first seven holes on a course softened by showers on his way to firing a two-under par 68 to stand atop the leaderboard at seven-under 133 after 36 holes at the $8 million event.
England's Rose, the US Open winner, birdied six of his last nine holes to fire a 66 and stand only one stroke behind playing partner Scott with American Simpson, the 2012 US Open winner, and Germany's Martin Kaymer, the 2010 PGA Championship winner, another two adrift.
Afternoon starters on the course in the hunt included US star Jim Furyk, England's Paul Casey, Canada's David Hearn and Thailand's Kiradech Aphibarnrat.
World number one Tiger Woods, who opened with a 71, took a bogey at the second hole that put him at two-over and on the cut line.
Despite Scott's sizzling start from the 10th tee, three bogeys prevented him from charging away from the field.
"If I was really hot with the putter, I really could have made it something to cherish," Scott said. "I should have made some of those putts the way the greens were rolling."
Scott opened with a chip-in birdie at 10 and sank a tricky 10-foot birdie putt at the par-5 13th using the belly putter than will be banned come 2016.
He rolled in a four-foot birdie at the 16th but missed a four-footer for par at 17, then went birdie-bogey at the second and third and again at the sixth and seventh holes.
Asked if he felt he would be the best player in the world if he could win his second major in four tries, Scott handed such honours to two players well off his pace: World number one Woods, a five-time winner this year, and second-ranked Phil Mickelson, with a British Open title and three wins.
"You look at a year like Phil and Tiger have had and they can both play better than me," Scott said. "But I'm putting myself in majors with a chance to win. It doesn't matter if I'm not the best player on the planet."
Aussie Jason Day and England's Lee Westwood made early charges, but Day settled for a 71 and stood five off Scott's pace while Westwood closed double bogey-bogey in a round of 73 to stand six strokes off the lead.
Westwood and Day have both endured several painful near-misses at majors, including at last month's British Open.
Rose opened bogey-bogey and followed a birdie at the 14th with a bogey at 18, but then the rain stopped and Rose ran off three birdies in a row, added another at the fifth and closed birdie-birdie to stay on Scott's heels.
"I was trying to hang on and stay alive out there," Rose said. "Water was coming down so hard it was in my face. At the turn the rain stopped and I could get back and really start playing my game."
Simpson flirted with the first 62 in a major championship before settling for a six-under par 64, matching the course record shared by Ben Hogan and Curtis Strange.
Simpson began on the back nine with back-to-back birdies, added another at the 14th and ran off four birdies in five holes in a streak that ended at the par-3 sixth.
In position to par the final three holes to match the record-low major round of 63, Simpson stumbled with a bogey at the seventh and parred his last two holes to lift himself from a share of 74th when the day began after an opening 72 to a spot only three shots behind Scott.
"I got off to a rough start but I've made my mark at the PGA Championship," Simpson said. "I felt comfortable with my game but I knew this course would demand everything I had."
US left-hander Mickelson fired his second 71, lamenting his inability to take advantage of the rain.
"With the greens so soft, you can attack the course," he said. "Unfortunately my game wasn't sharp enough to attack. Guys who are playing well, like Adam, like Justin, have a chance to pull away and guys who aren't hitting good shots are fading back."
Defending champion Rory McIlroy, enduring a season of struggles, started on the back nine and birdied four of his last seven holes for a 71 and a total of 140.
"That's two front nines I've played pretty good this week. If I get the back nine sorted out I'll be doing fine," McIlroy said. "Just try to get off to a fast start tomorrow, try to get something in the 60s and give myself a chance on Sunday."
Early results on Friday during the second round of the 95th PGA Championship at Oak Hill Country Club (par 70):
133 - Adam Scott (AUS) 65-68
134 - Justin Rose (ENG) 68-66
136 - Webb Simpson (USA) 72-64, Martin Kaymer (GER) 68-68
138 - Scott Piercy (USA) 67-71, Jason Day (AUS) 67-71
139 - Lee Westwood (ENG) 66-73, Zach Johnson (USA) 69-70
140 - Ryo Ishikawa (JPN) 69-71, Tim Clark (RSA) 69-71, Francesco Molinari (ITA) 72-68, Miguel Angel Jimenez (ESP) 68-72, Ryan Moore (USA) 69-71, Rory McIlroy (NIR) 69-71, Chris Kirk (USA) 71-69
141 - Matteo Manassero (ITA) 72-69, Boo Weekley (USA) 72-69, Thongchai Jaidee (THA) 70-71, Marc Warren (SCO) 74-67, Ian Poulter (ENG) 70-71
142 - Darren Clarke (NIR) 69-73, Vijay Singh (FIJ) 70-72, Phil Mickelson (USA) 71-71, Brendon De Jonge (ZIM) 71-71
143 - Brooks Koepka (USA) 71-72, Ken Duke (USA) 75-68, Brandt Snedeker (USA) 70-73, Danny Willett (ENG) 73-70, Harris English (USA) 74-69, John Merrick (USA) 75-68, DA Points (USA) 73-70, Gary Woodland (USA) 73-70
144 - Charles Howell (USA) 71-73, Nicolas Colsaerts (BEL) 71-73, Joost Luiten (NED) 71-73, Bubba Watson (USA) 70-74, Bae Sang-Moon (KOR) 75-69, Woody Austin (USA) 69-75, Martin Laird (SCO) 71-73, Chris Stroud (USA) 71-73
145 - Jimmy Walker (USA) 71-74, Luke Donald (ENG) 71-74, Mikko Ilonen (FIN) 73-72, David Muttitt (USA) 75-70
146 - John Huh (USA) 72-74, Russell Henley (USA) 76-70, Gonzalo Fernandez-Castano (ESP) 74-72, Carl Pettersson (SWE) 74-72, Graham DeLaet (CAN) 70-76, Charlie Beljan (USA) 71-75
147 - Brett Rumford (AUS) 70-77, Kevin Stadler (USA) 74-73, Richie Ramsay (SCO) 72-75
148 - Derek Ernst (USA) 72-76, Kohki Idoki (JPN) 72-76, Geoff Ogilvy (AUS) 74-74, Jordan Spieth (USA) 74-74
149 - Alex Noren (SWE) 76-73
150 - Tom Watson (USA) 73-77, Nick Watney (USA) 76-74, George Coetzee (RSA) 74-76, Chris Wood (ENG) 75-75
151 - Danny Balin (USA) 73-78, Kyle Stanley (USA) 73-78, Kevin Chappell (USA) 79-72
152 - Paul McGinley (IRL) 78-74, Lucas Glover (USA) 76-76, Mike Small (USA) 76-76
153 - Freddie Jacobson (SWE) 76-77
154 - Kirk Hanefeld (USA) 76-78
156 - Jeff Martin (USA) 78-78, Rod Perry (USA) 78-78, Sonny Skinner (USA) 76-80
159 - Mark Brown (USA) 77-82
160 - Chip Sullivan (USA) 84-76
163 - Lee Rhind (USA) 81-82
WD - Jamie Donaldson (WAL) 80, Angel Cabrera (ARG) 80