American Webb Simpson beat compatriot Chez Reavie in a play-off to win the Deutsche Bank Championship as England's Luke Donald finished two shots back.
Simpson shot a six-under 65 to end 15 under as Reavie bogeyed the 72nd for a 66 to take it to a shootout in Boston.
Both players birdied the first extra hole but Reavie could only make par on the second as Simpson, 26, birdied to clinch his second PGA Tour win.
Donald hit 67 for tied third with Jason Day (68) and Brandt Snedeker (66).
World number one Donald's chances of winning were scuppered with a double bogey on 12, but he has now finished in the top 10 in 11 out of his last 15 PGA Tour events.
Simpson's birdie on the last hole in regulation play put pressure on Reavie, who hit his wedge approach over the back of the green before chipping back on and holing from 10ft to salvage a play-off.
Simpson proved the most nerveless in the finale, nailing a long putt on the 18th before his approach at the 17th allowed him to make another birdie for his second win of the season.
"I told somebody that winning for a second time might be easier, but it was tough," he said.
Overnight leader Bubba Watson dropped down the leaderboard after hitting a final-round 74 but finished with a smile after sinking a long putt on the last for an eagle.
Ireland's Padraig Harrington and Northern Ireland's Graeme McDowell dropped out of the race for the $10m (£6.2m) FedEx Cup jackpot after finishing outside the top 70 in the overall standings who advance to the third and penultimate leg of the end-of-season Fed Ex Cup play-offs in Chicago in a fortnight.
Harrington carded a closing 75 to end three over in Boston, while McDowell paid a huge price for bogeying the 17th and missing a six-foot birdie putt on the last for a 71.
Donald was two behind Watson at the start of the day, but with the left-hander carding seven bogeys, he and playing partner Simpson fed off each other as both went out in 30.
But the Englishman, who was a joint runner-up last year, dropped another shot on 16 to slip out of the running.
The leading 70 players in the points standings move on to next week's BMW Championship in Illinois before the top 30 qualify for the Tour Championship finale in Atlanta.