Even Jason Dufner smiled when he won the US PGA Championship.

Dufner comes across as one of the most laid back people on the planet and rarely breaks from his deadpan swagger.

Even with the Wanamaker Trophy in hand the smile looked a little forced but the man who sparked an internet craze of 'Dufnering' - sitting stiffly and looking disinterested - insisted it was genuine.

And so it should be after the 36-year-old American with the quirky waggle made amends for losing out on the title in a playoff to Keegan Bradley in 2011, by claiming his maiden major title at Oak Hill Country Club on Sunday.

Dufner bogeyed the last two holes but shot a closing two-under 68 to finish at 10-under and win by two strokes from 2003 champion and overnight leader Jim Furyk (71).

Henrik Stenson (70) and countryman Jonas Blixt (70) finished third and fourth respectively as Sweden's long wait for a first major continues.

Australia's Masters champion Adam Scott carded five birdies in his final round but also notched up five bogeys for a 70, only good enough tie for fifth place.

Dufner's win came two years after he led by four with four holes to play but coughed up his lead then went down in the playoff.

"It feels great. My name will always be on the trophy and nobody can take that away from me," Dufner said.

"I come across as a pretty cool customer I guess but there are definitely some nerves out there, especially when you're trying to win a major championship."

Bradley, a key combatant in an ongoing friendly Twitter war, was on hand to hug his mate at the end.

Dufner was just happy to be able to lay to rest some of his 2011 demons from Atlanta Athletic Club.

"You always carry those scars with you and he always jabbed at me a little bit about having one of these (Wanamaker trophy) in his house and thanks me for giving it to him," Dufner said.

"Now I've got one too. It's pretty neat to come back and win the PGA."

For Scott, it was a missed opportunity in what has been an incredibly consistent run in major championships.

His five birdies would have been enough if they weren't mirrored by as many bogeys with the last throw of the dice no doubt coming on the par five 13th.

Looking to make the par five in two Scott came up just short in the rough before hitting a wedge fat and ultimately taking bogey when eagle or birdie was on his mind.

"I felt like I was still in there with a chance coming up 13, if I could do something special up there," Scott said.

"But the rough got me. I was in the long stuff too much today to really have a good chance. You can't escape it all the time."

Scott has been the best performed player to par in the majors over the last two years, finishing in the top 15 seven of eight times and claiming the Masters in April.

"It would have been nice to get another win in a major seeing I've kind of put myself in position, but I didn't," he said.

"So I have got to push on and try and win a couple other tournaments this year to feel like I really get something out of my good play."

Jason Day (67) had everyone all a flutter with a run of seven birdies in a 10-hole stretch but bogeyed the last three holes to fall to a tie for eighth at three-under.

Marc Leishman (68) is headed home for the impending birth of his second child on a great note, finishing at two-under in a tie for 12th.

Matt Jones (+4), Marcus Fraser (+5) and John Senden (+11) rounded out the Aussie tilt.

World No.1 Tiger Woods finished with a 70 to be four-over for the championship, well off the pace but he was better than world No.2 Phil Mickelson who finished with a 72 to be 12-over.