Needing a birdie on the par-4 18th for 59, Watney drove into the left rough, failed to reach the green with his approach and left his long birdie pitch just short of the putting surface.
The American finished at 22-under 262 and earned $1.3 million in the unofficial PGA Tour event, finishing one stroke ahead of 2011 champion Bo Van Pelt and Robert Garrigus and three ahead of Tiger Woods.
“I saw Tiger got off to a good start, so I wasn’t really thinking about winning when I teed off,” Watney said. “But the round sort of built momentum and things just kept getting better and better. I’m thrilled to have come away with the win.”
Van Pelt and Garrigus tied for second, each carding 66 after starting the last round sharing for the lead. Needing a birdie on 18 to force a playoff, Van Pelt saved par after heading into a greenside bunker.
After five birdies on the first seven holes, Woods finished with a 63 to tie for fourth at 19 under with Chris Kirk and Zimbabwe’s Brendon de Jonge. Kirk shot 67, and de Jonge had 66.
CHAMPIONS TOUR: In San Antonio, David Frost won the AT&T Championship, beating Bernhard Langer with a birdie on the second hole of a playoff after overcoming a six-stroke deficit Sunday.
Frost and Langer each shot 6-under 66 to finish at 8-under 208 on TPC San Antonio’s Canyons Course.
EUROPEAN TOUR: In Shanghai, Peter Hanson won the BMW Masters for his second win of the year, shooting 5-under 67 to hold off Ryder Cup teammate Rory McIlroy by a stroke.
Hanson finished at 21-under 267 on The Masters Course at Lake Malaren. McIlroy had 67.
LPGA TOUR: In Yang Mei, Taiwan, Suzann Pettersen won the Taiwan Championship for her second consecutive victory, rallying to beat Inbee Park by three strokes.
Pettersen closed with 3-under 69 at Sunrise.
WEB.COM TOUR: In McKinney, Texas, Justin Bolli closed with 6-under 65 to win the Tour Championship on Sunday. He moved into the top 25 on the money list with the $180,000 first prize to earn a PGA Tour card for next year.
Scott Parel shot 69 and tied for 28th at TPC Craig Ranch.