Rookie Ted Potter Jr clinched his first PGA Tour triumph on Sunday, beating fellow American Troy Kelly at the third play-off hole to win the Greenbrier Classic in West Virginia.

The 28-year-old Florida-born left-hander kept his cool to sink a four-foot birdie putt after the players had both finished on 16 under and then could not be separated on the first two extra holes.

Potter had burst into contention with a late surge at White Sulphur Springs, his eagle and two birdies over the final four regulation holes giving him a second consecutive round of 64.

Kelly signed for a 66 to earn a share of top spot after 72 holes, while third-round leader Webb Simpson slipped out of contention with a three-over 73.

The US Open champion, who held a two-shot advantage heading into the final round, endured a nightmare back nine, with four bogeys in five holes from the 12th ending his challenge.

Simpson finished five shots off the pace in a tie for seventh.

Simpson, who had scores of 65, 66 and 65 in his first three rounds, could not put his finger on why things had gone wrong on Sunday.

"I don't know," he said on "It's just the nature of the game. You go from not making any mistakes all week to making them all on the back nine."

The 26-year-old from North Carolina will now take a break - missing the Open later this month - because his wife is due to give birth to the couple's second child.

"It's one of those things where I'm going to take the positives from this week and the things that let me down today," added Simpson, whose next tournament will likely be the World Golf Championships-Bridgestone Invitational at the start of August.

"I'll take a look at that and try to go out and work on it. Every situation I've been in like this, where I've had a tough Sunday or a tough finish, I've been able to learn from it and it's helped me down the road."

Charlie Wi (65) and rookie Charlie Beljan (67) finished joint third, two shots adrift of Potter and Kelly.

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