Beginning the day in a four-way tie at the top of the leaderboard, the world No 41 posted a closing five-under 67 to finish 22-under in a congested field where five players tied for second.
Among those ending one-shot back were Charley Hoffman and Brendan Steele, who both stayed in contention with eight-under 64’s on the final day, while Steve Wheatcroft and South Korea???s Sung Joon Park also ended on 21-under.
Matt Kuchar completed the group of runners-up after a final round 67, with the 36-year-old missing an 11-feet birdie putt at the last to potentially take the tournament into a play-off.??
Needing par on the 18th to secure the trophy he previously won in 2010, Haas found his ball precariously placed on the edge of a bunker from the tee shot.
The American considered various unorthodox shots before safely punching the ball out, with a well-measured third shot leaving Haas two putts from 20 feet to take the title.
“I can’t tell you what I was thinking,” Haas told Sky Sports 4 when reflecting about his final hole. ???It was a bad drive.
???To end up there (on the ridge of a bunker) was pretty bad luck. It was a terrible break but maybe deservedly so with the bad shot.”
???On the last hole I was grinding it out to the end. Sixteen was huge (where Haas hit a birdie). I needed that one to give me a chance.
???I called my wife before the week started and said I didn’t think I’d be able to score this week. This is unbelievable. This is great.”
Rookie Justin Thomas, who shared the third-round lead with Haas, Erik Compton and first-round leader Michael Putnam, ended with a three-under 69??and tied for seventh with Webb Simpson and Boo Weekley.
While Haas’ win is his sixth PGA Tour title in as many years, the lowest score of the final round came via a nine-under 63 from Colt Knost.??
???I played great today,??? Knost said, who qualifies for next week???s Phoenix Open with a top 10 finish. ???I hit it awesome.
???I honestly think I left a couple out there, but really happy with the result.
Phil Mickelson marked his first competitive appearance in four months by finishing seven shots back on 15-under, level with world No 15 Patrick Reed and three clear of compatriot Keegan Bradley.