World number two Phil Mickelson held his nerve at the second play-off hole to edge out English duo Ross Fisher and Lee Westwood to win the HSBC Champions in Shanghai and claim his first overseas title in 14 years.

Overnight leader Mickelson held a five-stroke advantage over Fisher through seven holes of his final round, but dropped six shots in eight holes to hand Fisher a one-stroke advantage heading up the last.

After Fisher shot a double bogey at the last and Mickelson could only manage a bogey six after finding water with his second shot, the pair dropped to 10-under-par overall and a three-way tie with Westwood.

Westwood had stormed up the final round leaderboard with a final round five-under-par 67, which included six birdies on the back nine.

All three had birdie chances at the first play-off hole, but after Westwood and Mickelson both narrowly missed, Fisher held his nerve to two-putt from eight feet.

At the second play-off hole, Westwood found water at the front of the green and Fisher hit his second into greenside bunker, with Mickelson on the fringes of the green.

Westwood, following a drop, played his fourth shot through the green and agonisingly down the slop into the water, while Fisher chipped out of the bunker to within eight feet in four.

But Mickelson played a deft flop to four feet with his third, and after Fisher missed, the American holed his birdie putt to claim the $833,300 first prize and 'Champion of Champions' title.

American Kevin Stadler finished fourth at nine-under, with Open champion Padraig Harrington a shot further back with Vijay Singh after a final round one-under-par 71.

Paul Casey, playing in the final group with Fisher and Mickelson, endured a nightmare fourth round and carded a six-over-par 78 to slip to five under.

Mickelson crucially grabbed a birdie at the par-four 16th to cut Fisher's lead to just one before his bogey at the last left the three-time Major winner two over par for his final round.

"I had a huge lead early in the round, but I hit some horrible shots. I had six penalty strokes in the final round, which made it a difficult day. But I kept fighting, and it's a funny old game golf, you never know what's going to happen," said Mickelson, who had previously claimed just one title away from American — the 1993 Tournoi Perrier Paris title on the European Challenge Tour.

"I never thought after hitting the water I had a chance, but it happened and I'm very thankful to be the recipient of this year's championship trophy.

"It feels amazing I don't know how it happened. The whole day was a whirlwind, but what a fun day and what a fun opportunity to come and play here in China."