Australian Marc Leishman produced an eight-under-par 62 to win the Travelers Championship by one shot, his first victory on the PGA Tour.
Leishman, ranked 160th in the world before his breakthrough success, carded eight birdies at the TPC River Highlands to finish the tournament at 14-under overall.
He was one stroke ahead of American duo Charley Hoffman and Bubba Watson, the latter turning in his best performance since winning the US Masters in April.
Hoffman, who was two shots ahead of clubhouse leader Leishman with two holes remaining, threw away his advantage in Cromwell, Connecticut.
Having played a flawless round before the 17th, Hoffman ended with a double bogey at 17 and a bogey at 18 to hand Leishman the trophy.
The 28-year-old, from Warrnambool, Victoria, made seven birdies in his first 14 holes to surge from 20th to the top of the leaderboard.
He had another birdie again on the 17th in an ice-cool bogey-free round, but was forced to wait over two hours as clubhouse leader before being crowned champion.
"When I finished I didn't know whether it would be good enough. I was pretty confident it wouldn't be," Leishman said.
"But it is a funny game and I can't believe it right now."
The result was the fifth time in seven years a player has won his maiden career title at the Travelers Championship and was the first victory by an Australian on the US Tour in 2012.
Leishman is only the second Australian to clinch the title, with Greg Norman the only other winner in 1995.
He received $US1.08 million for the win - more than double his earnings to date this season.
Elsewhere in the field, Stuart Appleby slipped from third overnight to equal 18th with a two-over final round of 72, while fellow Australian Nathan Green dropped four places to equal 24th with a one-under 69.
Aussie duo Greg Chalmers and Aaron Baddeley finished the week tied 37th at five under.