ROCHESTER, New York (AFP) - American Jason Dufner matched the low 18-hole score in major golf history on Friday, firing a seven-under par 63 to take the clubhouse lead at the 95th PGA Championship.

On an Oak Hill Country Club course that was drenched by rain showers all morning, Dufner fired five birdies and an eagle to stand two strokes atop the leaderboard at nine-under 131 for 36 holes in the US$8 million (S$10 million) tournament.

Dufner became the 24th player to shoot 63 in a major. The feat has been done 26 total times, with Australian Greg Norman and Fiji's Vijay Singh accomplishing it twice.

Jack Nicklaus, Tiger Woods, Rory McIlroy, Nick Price and Nick Faldo are among the other players to shoot 63 in a major.

"That's pretty good company right there," Dufner said.

Dufner's round also set a course record at Oak Hill, breaking the mark of 64 shared by fellow Americans Ben Hogan from the 1942 Times-Union Open, Curtis Strange from the 1980 US Open and Webb Simpson earlier on Friday.

Dufner had a 12-foot birdie putt at the 18th hole to shoot 62 but left it 18 inches short and his tap-in for par and 63 dropped in off the right edge of the cup.

"You don't want to leave anything short to make history," Dufner said. "But I was able to two-putt and at least share history."

Australian Adam Scott, the reigning Masters champion, and American Matt Kuchar were in the clubhouse on 133 while Jim Furyk, who co-led with Scott after a 65 on Thursday, was at eight-under with two holes remaining in his second round.

England's Justin Rose, the reigning US Open champion, was on 134.

Dufner holed his approach shot for an eagle at the par-4 second and followed with back-to-back birdies at the par-5 fourth and par-4 fifth.

On the back nine, Dufner birdied the par-3 11th and par-5 13th, then birdied the par-4 16th. He missed a 15-foot birdie putt at the 17th, setting up the drama at 18.

Dufner won his first US PGA title after 163 tries last year at New Orleans, then followed by taking the Byron Nelson Championship.

Dufner shared fourth at the US Open in June and lost the 2011 PGA Championship in heartbreaking fashion.

Owning a four-stroke lead on the field with four holes to play at Atlanta Athletic club, Dufner led eventual winner Keegan Bradley by five strokes, but Dufner made bogeys at 15, 16 and 17 while Bradley birdied 16 and 17 to set up a three-hole aggregate play-off.

Bradley birdied 16 again, Dufner made bogey at 17 again and Dufner's birdie at 18 was not enough to avoid a one-shot defeat when Bradley parred the last.

Kuchar made five birdies but closed with a bogey to fall two back of Dufner.

"This was definitely the good side of the draw," Kuchar said. "People took advantage of the conditions to make some birdies."

World number one Tiger Woods, who opened with a 71, was one-under on his second round through 17 holes.

Despite Scott's sizzling start from the 10th tee, three bogeys on holes immediately after birdies 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." 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 in the hunt.

"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 a 62 as well. He 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. But Simpson stumbled with a bogey at the seventh and parred his last two holes.

British Open winner Phil 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."

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.