(CNN) -- Keegan Bradley beat fellow American Jason Dufner in a three-hole playoff to win the U.S. PGA Championship in Atlanta Sunday.
The 25-year-old from Vermont finished one-under-par over the 16th, 17th and 18th holes at the Atlanta Athletic Club to hold off Dufner by a shot and claim his first major title.
He is the seventh first-time major winner in a row, a record, and the first player from the United States since Phil Mickelson at the Masters in 2010 to lay claim to one of golf's majors.
Bradley, a rookie in his first season on the PGA Tour, found his victory hard to take in, particularly as he was playing in a major for the first time, his place sealed by claiming the Byron Nelson Championship back in May.
"I can't believe it," he said. "I feel so proud."
When Bradley, who is the nephew of LPGA legend Pat Bradley, triple-bogeyed the 15th in regular play, his chances looked over.
He trailed Dufner, who was 11-under, by five shots with just four holes to play.
But as Dufner proceeded to card three careless bogeys in a row, Bradley birdied the 16th and 17th and parred the treacherous 18th to set the clubhouse target on eight-under 272 after a 68.
Dufner bravely holed out for a par on the 18th for a 69 to force the playoff but was immediately behind, as Bradley birdied the 16th.
When Dufner bogeyed the 17th to fall two shots behind his challenge looked over, but he rattled home a birdie putt on the last to force Bradley to two-putt for par and a remarkable victory.
Dane Anders Hansen powered through the field on the last day for a 66 to finish third on seven-under-par.
Fellow Scandinavian Robert Karlsson of Sweden looked a possible winner as he got to eight-under, but a run of three bogeys dropped him into a tie for fourth with 2001 PGA winner David Toms and another American, Scott Verplank, on five under.
English pair Luke Donald and Lee Westwood, respectively No. 1 and No. 2 in the world, both threatened on the final day, but mistakes cost them dear on the back nine, as they shared eighth on three-under, a shot behind last week's WGC Bridgestone winner Adam Scott of Australia.
Brendan Steele, who started the day as joint overnight leader with Dufner, fell away with a 77 and ended in a large group on level par, which included Mickelson.