David Gossett fired a five-under-par round of 66 to win the John Deere Classic by one stroke after holding off a persistent challenge from Briny Baird.
Playing on a sponsor's exemption, the 22-year-old 1999 US Amateur champion grabbed the tournament lead with a second-round 64 and held on to it to finish on 19-under-par 265.
Gossett sank a five-foot par putt to hold off Baird on the last hole after the pair had gone head-to-head down the back nine. Baird also shot a 66 en route to his career-best finish. He was alone in second at 18-under 266.
"This is what I've been dreaming of for so long -- a putt to win a golf tournament," Gossett said.
Gossett's win, which came in just his fifth PGA Tour appearance this year, gives him a two-year exemption on the main tour after playing most of the year on the Buy.com Tour.
He becomes the third non-PGA Tour player to win a tournament this year and the first with a sponsor's exemption since Tiger Woods was victorious at Las Vegas in 1996.
Looking like a man destined to win, Gossett strolled the rolling, tree-line fairways of Deere Run with an air of extreme self-confidence.
And with good reason. Prior to this week, he had six top-ten finishes on the junior tour, including his last four events. He realised his dream in only his 12th professional event but it wasn't the dream he expected it to be.
"In the dream, you always do something spectacular," Gossett said. "You're always hitting a nice high 4-iron over water to three feet to win on the last hole."
In contrast to Gossett, Baird said he was nervous playing in the final group.
"I definitely was uptight," Baird said. "The first tee was kind of tough. I settled down for a while but then I kept thinking to myself, 'when is this going to be over?'"
"I was thinking, 14 more holes, 13 more holes...If you would have told me last night that I would have been in the bunker on the final hole one back hitting over water, I may have thrown up."
Pete Jordan finished third at 17-under 267, a stroke ahead of Jeff Sluman and two better than Matt Gogel and Ian Leggett.
With the tour's best players skipping this event the week after The Open at Royal Lytham, eight of the top nine players on the leaderboard entering the day had never won.
Las Vegas-based Briton Edward Fryatt had shown signs of challenging Gossett after three rounds with scores of 66,67 and 69 but he faded to a level par 72 to finish in a tie for 15th on ten under par with a consolation cheque of $38,136.