Graeme McDowell tripped to a bogey at the 18th to force a playoff with Webb Simpson, but atoned for his mistake by parring the first playoff hole to win the RBC Heritage.
McDowell finished his final round with a 2-under 69, while Webb Simpson shot an even-par 71 as each finished 72 holes at Harbour Town Golf Links at 9- under-par 275.
"I played nicely all week," said McDowell. "The putter was cold most of the weekend, but I really got it going today."
Luke Donald (69) and Kevin Streelman (72) shared third at 7-under, and Jerry Kelly took fifth at minus-6.
Third-round leader Charley Hoffman struggled during Sunday's windy conditions to card a 6-over 77 and fall into a tie with Russell Henley (69) and Chris Stroud (70) for sixth place at 5-under.
Hoffman held a 1-stroke lead over McDowell early in his back nine until Hoffman's bogey at the 12th coupled with Simpson's birdie at the same hole made it a three-way tie for first at 9-under.
Hoffman fell apart from there, hitting his drive at the 14th into the water en route to a double bogey to drop two strokes off the pace.
He then closed with back-to-back bogeys at the 17th and 18th to slip further down the leaderboard.
McDowell briefly took the outright lead after rolling in a birdie putt at the 16th, but he had his 13-foot par putt at the last settle two inches from the hole and he tapped in for a bogey to finish at 9-under.
Simpson, meanwhile, followed his birdie at the 12th with six straight pars.
Simpson did have a chance for the outright win with a 22-foot birdie putt at the 18th, but it rolled just past the left side of the hole and he converted a short par putt to necessitate the playoff.
"I never thought I made a putt more than that birdie putt," Simpson said about his potential winning putt.
They replayed the 18th for the playoff, where McDowell's second shot found the green while Simpson hit his to the right of the target.
After Simpson's effort from off the green rolled just past the left lip of the cup, McDowell's 12-foot birdie putt settled inches short of the cup and he tapped in for par.
Simpson then failed to keep the playoff going as he could not to convert a 6- foot par putt to hand McDowell his second career win on the PGA Tour.
"You're never out of this tournament. You just have to hang around and hang around, and I did that," McDowell said. "I'm really disappointed for Webb. He had a great first putt there in this playoff hole and he got a terrible gust of wind and it rolled another three or four feet."
The top of the leaderboard was fluid all day, starting with Simpson rolling in consecutive birdies at the second and third to join Hoffman in the lead at 11- under before Hoffman's bogey at the fourth dropped him a shot off the pace.
The two traded spots at the fifth with Hoffman's birdie coupled with Simpson's bogey, but Hoffman lost his 1-stroke lead with a bogey at the sixth to put them both at 10-under.
Hoffman regained his outright lead at the eighth when Simpson 2-putted for bogey.
McDowell, meanwhile, had nine pars and two birdies over his first 11 holes, capped with a 28-foot birdie putt, to move into a tie with Simpson for second at 9-under before Simpson's bogey at the 10th set up the three-way tie at the 12th.
NOTES: It was the fourth playoff this season on the PGA Tour ... McDowell was playing in his first career playoff, while Simpson fell to 1-3 in playoffs ... Hoffman has not won since the 2010 Deutsche Bank Championship. He does have seven top-10 finishes in that span ... It was the 11th playoff in the 45-year history of the RBC Heritage.