Mickelson made a 6-foot birdie putt on the second extra hole -- the par-5 18th -- to take the $833,300 first-place check in the $5 million tournament. The victory was his fourth of the year, following three wins on the PGA TOUR.
'It feels amazing,' Mickelson said. 'I don't know how it happened. The whole day was a whirlwind, but what a fun day.'
The win gave Lefty something that eluded top-ranked Tiger Woods, absent this year after finishing second the last two seasons.
'I had a huge lead early in the round, but hit some horrible shots,' Mickelson said. 'I had five penalty strokes, actually six in the final round. And it was a difficult day. But I kept fighting and it's a funny game, golf. You just never know what's going to happen. We say that a lot.'
Fisher had already played four shots when Mickelson holed out. Westwood dumped two in the water and was out of it when Mickelson holed his winning putt.
The finish was a wild one for the second-ranked Mickelson, playing his second straight tournament in Asia, while combining a family holiday with some golf. Last weekend in the Singapore Open, he finished 16 strokes off the pace.
Mickelson had a five-stroke advantage on the front nine and was three ahead after 11 holes, but dropped four shots on 12, 13 and 15. On 15, his bogey and Fisher's 3-foot birdie putt gave the Englishman a two-stroke lead with three holes to play.
Mickelson got one shot back with a birdie on the 16th. On 18, despite hitting his second shot into the water, he still had a chance to win. But a 10-foot putt for par -- which would have left the American alone at 11 under -- slipped just by. He finished with a 4-over 76 for a 10-under 278 total.
'I never thought after hitting in the water I had a chance, but it happened,' Mickelson said.
Fisher, ranked No. 141, went to 18 with a one-stroke lead over Mickelson. Trying to reach the par-5, 538-yard hole in two, he landed his shot in deep rough to the left of the green. He chipped his third onto the green, but it bounced through and rolled into the water hazard on the opposite side. He took a penalty drop and needed a chip and two putts for a double bogey to finish at 74.
Westwood, nine strokes behind Mickelson after three rounds, made six birdies on the back nine -- and missed two other opportunities on 17 and 18. He finished with a 67 and was in the clubhouse relaxing when he was called back for the playoff.
On the first playoff hole, Fisher missed an 8-foot birdie attempt at 18 that would have won the tournament. Westwood and Mickelson missed longer birdie attempts.
Mickelson said he planned to leave China just after the tournament and would take 2 1/2 months of vacation. Part of the trip to China was used to sightsee with his family, as well as test new equipment for next season.
'So, I feel like I have a head start for '08,' he said.