Kevin Na won his first PGA Tour event since 2011 as he shot a final-round six-under 64 for a five-stroke victory at The Greenbrier in West Virginia.
Five birdies in six holes on the front nine put Na in control and he finished at 19-under-par 261 at The Old White TPC for his second career win.
Third-round co-leader Kelly Kraft carded an even-par 70, which included a birdie at the par-3 18th, to claim second place at 14 under.
Fellow Americans Brandt Snedeker (64) and Jason Kokrak (67) tied for third at 13 under.
Kraft, Snedeker, Kokrak and Austin Cook (66) – who was in a group of five tied for fifth at 12 under – earned places in The Open Championship starting at Carnoustie on July 19 thanks to their performances at the tournament.
The win ended a seven-year drought for the 34-year-old Na, who won the Shriners Open in Las Vegas and despite some close calls had not taken home a trophy since.
"It feels amazing. I see the record every time on TV; the most top fives, the most top 10s without a win," he told the Golf Channel.
"I'm always up there. I've been close so many years and failed so many times," said the Korean-born Na, who turned pro at age 17.
"It took me eight years to win the first time and at the time I told everyone it would not take me eight years to win another one. And it took seven."
Na's spectacular putting was the difference on Sunday as he negotiated the hard, fast greens under sunny skies in West Virginia better than Kraft, whose three-putt bogey on the 14th all but ended his hopes of a maiden PGA Tour victory.
"I never got ahead of myself... Things were just happening and for some reason I felt like it was my day," he said.
Phil Mickelson, in his first tournament since his bizarre US Open final day meltdown on the 13th green, was penalised two shots on Sunday for improving his line of play.
Before teeing off on the par-4 7th he stepped on a tuft of grass, which he later told rules officials was in his preferred line, leading to the penalty.
Mickelson had three bogeys, a double bogey and a triple bogey on 18 to go with four birdies for a final-round 74 to finish the tournament tied for 65th.
Australia's lone representative on the weekend, Cameron Percy, made four bogeys and just two birdies on Sunday in his two-over-par 72 to end his tournament at two under in a tie for 56th.