Final leaderboard: -16 N Watney (US) -14 D Johnson (US) -13 A Hansen (Den), F Molinari (Ita) -12 M Kuchar (US) -11 A Scott (Aus), L Donald (Eng) -10 R Fowler (US)
Selected others: -8 T Woods (US), P Harrington (Ire), M Laird (Sco), R McIlroy (NI) -6 L Westwood (Eng), P Casey (Eng) -4 M Kaymer (Ger) +1 J Rose (Eng), G McDowell (NI) +2 I Poulter (Eng) +7 R Davies (Wal), R Fisher (Eng)
Nick Watney overhauled fellow American Dustin Johnson to win the WGC Cadillac Championship in Florida.
Watney birdied the 18th for a five-under 67 to end 16 under and go one better than his runner-up spot in 2009.
Overnight leader Johnson (71) ended 14 under with Dane Anders Hansen and Italy's Francesco Molinari 13 under.
England's Luke Donald, tied second overnight, could only manage a level-par 72 for 11 under, while Tiger Woods shot 66 to end 10th at eight under.
The big-hitting Johnson led Watney, Donald and another American Matt Kuchar by two shots after round three, and was tied for the lead with Watney heading into the final few holes before ceding the initiative when he made his first bogey on the 16th.
Watney lost out narrowly to Phil Mickelson at Doral two years ago after finding water on the last, but he made no mistake this time around and holed from 10ft for birdie leaving Johnson needing to hole his second shot from back down the 18th fairway to force a play-off.
But Johnson could only make par and handed Watney his third PGA Tour win and the biggest title of his career after blowing a three-shot lead going into the final round of the US PGA with a closing 81 last year. Johnson himself led by three before taking 82 in the final round of the US Open last year.
"I'm not sure about it owing me one, but I felt I had something for this course and I think I settled the score," said the 29-year-old Watney.
"It worked out great and I couldn't ask for a better ending."
Kuchar (71) ended 12 under with Australian Adam Scott (71) alongside Donald on 11 under and American Rickie Fowler (66) 10 under.
Donald needed to win to move ahead of Lee Westwood to number two in the rankings, but was unable to add a second straight WGC title to his Match Play win last month.
The 33-year-old dropped a shot via the water on the third and cancelled out birdies on five and eight with two further bogeys at the 11th and 13th.
Hunter Mahan (73) was nine under while also at eight under alongside Woods were Ireland's Padraig Harrington (73), Scotland's Martin Laird (73) and Northern Ireland's Rory McIlroy (74).
Former world number one Woods has now gone 19 events and 16 months without a victory but his climb from 30th gave him a much-needed boost ahead of the Masters which begins on 7 April.
"It's progressing. I'm still building, still putting the pieces together, which is nice," said the four-time Masters champion.
"I hit a lot of good shots and when I did miss it I knew how to fix it.
"That feels good and I got up and down a lot. Those are key to be able to keep the momentum in the rounds going.
"My trajectory is becoming better and my shapes of my shots are getting tighter.
"The driver is still not quite there. I'm not quite shaping the golf ball like I want to yet, but I'm hitting it flush again, so that's just a matter of time before that comes around."
Of still not being in contention he added: "Of course it bothers me. I want to win golf tournaments - that's the whole idea of entering events.
"Every tournament that I've played this year, I've felt better coming out of it, even though the results have not been good."
Harrington's round included two trips to the water on the third for a triple-bogey seven after he had opened with a 15ft eagle putt to be in a tie for second. The 21-year-old McIlroy had also tasted second after a birdie on the first but repeated trips to the sand scuppered his chances.
Westwood held onto his world number two spot and also gave his confidence a boost with a 68 for six under.
Phil Mickelson closed with a 76 to end four over and has now gone 22 events, stretching back to last year's Masters, without a win.