Keith Mitchell claimed his maiden PGA Tour victory after claiming the Honda Classic with a 15-foot birdie putt.

Mitchell reached the 18th green and had a 15-foot putt for birdie – and the win – with seasoned professionals Brooks Koepka and Rickie Fowler sharing the lead on Sunday.

The 27-year-old Mitchell kept his nerve as he holed the putt for a one-stroke win at the PGA National Resort and Spa in Palm Beach, Florida.

Mitchell carded a final-round 67 to finish nine under overall, breaking through for his first PGA Tour title, having spent time on the Tour, and PGA Tour Latinoamerica.

"I was just trying to focus on what's going on," Mitchell said after his round that started with back-to-back bogeys. "My mind started to wonder there at the very end."

Koepka (66) and Fowler (67) finished in a tie for second, while Ryan Palmer and Lucas Glover were tied for fourth at seven under.

Two-time reigning US Open champion and US PGA Championship holder Koepka had five birdies and a bogey on the final day.

Fowler – who also carded two bogeys on the front nine and another after the turn – birdied three of his last four holes to remain in contention until Mitchell's final stroke.

Vijay Singh, 57, entered Sunday in second place and would have been the oldest player to win on Tour, but the veteran fell down to sixth place after his scorecard was stained with four bogeys.

Singh worked his way back up the leaderboard but could not catch the young field. He ended the weekend in sixth place following his even-par 70.

Sergio Garcia (69) ended the tournament five shots off the pace, while last year's winner Justin Thomas shot even par in his final round and finished tied for 30th.