Matt Kuchar holed a bunker shot on the 18th at the RBC Heritage to claim the title by one shot from Luke Donald who came up just short at Hilton Head yet again.
Kuchar had finished in the top-five in his last three events, including losing to Australian Matt Jones in a play-off at the Shell Houston Open two weeks ago.
But a front-nine 30 and a stunning shot on the last saw the American finish on 11 under with a closing 64 and deny Donald, who had twice recorded second and third-place finishes here in recent years, his first win on the PGA Tour since the Transitions Championship in 2012.
Graeme McDowell shot a final round of 70 for a two under par ll finish
The 35-year-old looked like he would be going to a play-off for the second time in three weeks after a three-put bogey on the par-three 17th but a birdie on the last and Donald's failure to pick up a shot on his last four holes meant Kuchar won his seventh Tour title.
Birdies on the first, second, fourth, sixth, eighth and ninth holes, and a further one at the 10th, propelled Kuchar to 11 under for the tournament and a three-shot lead just after the turn.
A run of six pars followed and when he hit his tee shot on 17 to inside five feet, it looked certain Kuchar would go up the last with a two-shot lead.
A disastrous three-putt was to follow, however, and Kuchar also found the bunker with his second-shot at the par-four last before his stunning sand-rescue found the bottom of the cup and left Donald coming up the 15th one behind.
The normally mild-mannered Kuchar could not hide his delight as he punched the air when the shot went in and he admitted it was a relief after his mistakes on 17.
"It was just pretty disappointing, it felt like a two-shot swing," he told Sky Sports 4.
"I wasn't too disappointed to end up in that front greenside bunker on 18. That was a decent leave, I knew it was a pretty easy up and down.
"I said 'I'm about due to make one of these' and it was so cool to see that thing disappear at the end."
Donald had led by two overnight and birdied the second but a double-bogey on the par-four sixth stalled his momentum before birdies at seven and nine got him to the turn in 35. Another bogey followed on 10 but birdies on 11 and 12 put the 36-year-old within a shot of the lead before Kuchar's error had him back at the top of the leaderboard.
The Englishman made pars at 15 and 16 and stood on the 17th tee knowing he had birdied the hole in his first three rounds but his tee shot came up short of the ridge on the green leaving a 28-foot putt for birdie.
The putt had the weight but settled by the side of the hole and Donald had to settle for a par, a score he would repeat on the last to hand the title to Kuchar.
"I hit a lot of solid shots, a lot to build off and I'm excited about some of the changes I've been making," he said.
American Ben Martin hit a 67 to finish a shot behind Donald alongside countryman John Huh who closed his week with a 68.
US Amateur champion Matt Fitzpatrick ended his tournament with 18 pars in his final round, emulating Sir Nick Faldo who did the same to win the 1987 Open Championship at Muirfield.
The 19-year-old from Sheffield did not produce quite the same result as he ended the tournament nine shots off the lead at two under but will consider himself happy with the past 11 days after missing the cut by just one shot at the Masters.