|Wyndham Championship final leaderboard|
|-22 JT Poston (US); -21 W Simpson (US); -20 BH An (Kor); -19 V Hovland (Nor); -17 SW Kim (Kor)|
|Selected others: -15 P Casey (Eng); -13 P Reed (US)|
American JT Poston finished the Wyndham Championship without dropping a shot and secured his first PGA Tour title by one stroke in North Carolina.
The 26-year-old world number 164 carded an eight-under 62 to finish 22 under.
Poston is the first player since Lee Trevino in 1974 to finish bogey-free for 72 holes and win on the PGA Tour.
An Byeong-hun, who led after each of the first three rounds, began the final day one ahead but the South Korean made two late bogeys in a 67 and was third.
Englishman Paul Casey double-bogeyed the 10th and finished seven shots back in joint 13th after a closing 69.
An, also seeking his maiden PGA title, had not dropped a shot throughout the tournament until he took an unplayable lie in the rough at the 15th and recorded a bogey six to slip two shots off the lead.
He rolled in a long birdie putt at the next but with Poston in the clubhouse one shot ahead, An found the trees at the last and was faced with a 58-foot birdie putt to force a play-off, which clipped the pin but raced past as he took two more to finish.
Former US Open champion Webb Simpson birdied four of the final five holes to finish second behind North Carolina native Poston.