JB Holmes shot a final round 64 to set a clubhouse target of 16-under-par at the Shell Houston Open.
Overnight leader Jordan Spieth was the main contender as the tournament reaches its closing stages.
The in-form 21-year-old has five top 10 finishes from his seven tournaments this year and was looking for his second PGA Tour title of the year having won the Valspar Championship last month.
The young American dropped off the pace as he failed to match Holmes’ birdie barrage.
Holmes made eight birdies in his round to charge up the leaderboard and set a stiff target for the later starters.
Spieth mixed a birdie and a bogey in his front nine to remain at 14 under but birdies at 13 and 14 brought him level with Holmes and with two holes to go they remained locked together.
Johnson Wagner was a shot behind on the final tee with another American, Russell Henley, safely in at 14-under after a 69.
Paul Casey finished best of the Europeans after a 71 yesterday saw him finish the tournament at 12 under.