The 26-year-old American won his 12th US PGA Tour title despite bogeying two of the last three holes in regulation.

He birdied the third extra hole to beat Reed after defending champion Schauffele was eliminated on the first play-off hole.

The trio had finished 72 holes with 14 under par totals of 278.

The tournament only features players who won on the PGA Tour last year and Thomas, the 2017 champion, enjoyed a two-shot lead with three to play, but dropped one at the 16th and then had a bogey six at the par-five 18th in a four-under-par 69.

Playing partner Schauffele, the world number eight, reached the final green in two, but missed a seven-foot birdie putt for victory, carding a three-under 70.

Reed, ranked 11, was already in the clubhouse on 14 under after capping a bogey-free seven-under 66 with a 20-foot birdie putt at the 72nd hole.

The 2018 US Masters champion had putts to win on each of the first two play-off holes but was unable to get efforts from 30 feet and 12 feet to drop.

"For some reason I was supposed to win this week. I got very, very lucky," said Thomas.

"I truly felt like through 15 holes it was one of the best rounds I ever played."

He started the day one stroke off Schauffele's lead before a run of six birdies in eight holes.

"He was hitting ridiculous shots, making good putts in the wind, and he deserved the lead he got," said Schauffele.