Los Angeles - Branden Grace fired seven birdies in a five-under par 66 on Sunday to surge to his first PGA Tour victory at the RBC Heritage in Hilton Head, South Carolina.
South Africa's Grace, owner of seven European Tour titles, finished with a nine-under total of 275, two strokes ahead of Scotland's Russell Knox and England's Luke Donald - the 54-hole leader who yet again was pipped at the post on the Harbour Town Golf Links.
Donald now has five top-three-finishes in the Heritage but no victories.
He began the day seven-under and ended there, too, after a round that included two birdies and two bogeys in a four-hole stretch.
Grace, meanwhile, wasted no time in challenging Donald's lead, with birdies at his first two holes.
He bounced back from a bogey at the fourth with birdies on the next two holes and another on the ninth to take the lead into the back nine, where he made two birdies and a bogey coming in.
It was a good turnaround for the 14th-ranked Grace, after he missed the cut at the Masters last week.
He said putting was the difference, but it wasn't until he had rolled in a 10-foot birdie putt at 12 and a nine-footer at 13 that he really felt he had a victory in sight.
"When I got to 12, 13, when I made a couple of nice putts I knew I'm in there with a chance," said Grace, who finished equal fourth at the US Open last year and third at the PGA Championship.
"That last stretch of five holes you know you can't really force things. As soon as you try to force things there it's going to backfire. You just have to stay patient and grind it and that's what I managed to do."
Knox claimed his share of second with a final-round 67. He and Donald were two shots in front of Kevin Na, who carded a 69, and Bryson DeChambeau, who closed with a 68 for his share of fourth in his professional debut.
World number one Jason Day of Australia, who shot himself out of contention on Saturday with a season-worst 79, finished on a solid note with a three-under par 68.
Day finished tied for 23rd and will retain his world number one ranking as he heads into a much needed week off.
Leading final-round scores on Sunday in the US PGA Tour RBC Heritage at Harbour Town Golf Links in Hilton Head, South Carolina (USA unless noted):
275 - Branden Grace (RSA) 66-74-69-66
277 - Russell Knox (SCO) 72-65-73-67, Luke Donald (ENG) 66-71-69-71
279 - Bryson DeChambeau 70-69-72-68, Kevin Na 73-71-66-69
280 - Bryce Molder 70-70-73-67, Kim Whee (KOR) 71-72-68-69, Jason Kokrak 71-68-68-73
281 - Ricky Barnes 71-68-74-68, Aaron Baddeley (AUS) 71-69-73-68, William McGirt 69-71-72-69, Kevin Chappell 68-68-75-70, Matt Kuchar 67-71-72-71
282 - Ernie Els (RSA) 72-71-73-66, David Toms 69-73-71-69, Colt Knost 73-70-70-69, Graham DeLaet (CAN) 69-70-72-71, Kim Si-Woo (KOR) 68-72-71-71, Tyler Aldridge 71-73-67-71, Bill Haas 69-72-69-72, Charley Hoffman 68-68-71-75, Patton Kizzire 69-68-71-74
283 - John Senden (AUS) 71-73-74-65, Jason Day (AUS) 67-69-79-68, Morgan Hoffmann 70-69-74-70, Charles Howell 69-75-70-69, Chad Campbell 71-69-73-70, Russell Henley 72-67-71-73, Chris Kirk 72-66-71-74
284 - Adam Hadwin (CAN) 73-73-67, Marc Leishman (AUS) 71-72-68-73