Phil Mickelson birdied the second play-off hole to claim the HSBC Champions in Shanghai after a back nine full of drama.

With a five shot lead and only 11 holes to play victory looked assured for Mickelson, but the American had to rely on a play-off victory over Englishmen Ross Fisher and Lee Westwood.

Mickelson looked comfortable at the top of the leaderboard for much of the front nine and none of the chasing pack threatened his lead. He then dropped six shots in the next 8 holes to bring a number of players back into contention.

After a steady, if not spectacular, 17 holes Ross Fisher found himself a shot ahead with one hole to play. After both Mickelson and Fisher both hit good drives on the par 5 18th, the Englishman hit a brave second shot just off the green. Mickelson then found water and his title hopes seemed to be over. Fisher had a tricky lie and in an unbelievable turn of events pitched his ball into the water.

Mickelson was eventually left with a chance for par to win the tournament but missed and Fisher then holed a brave putt for a seven to tie at the top.

Lee Westwood was the third member of the trio involved in the play-off. Incredibly the Englishman began the back nine 12 shots behind the leader. He came back in 30 to post an exceptional round of 67, the lowest score of the day.

All three players made par at the first play-off hole and headed back up the 18th for the third time on Sunday. Fisher and Westwood both missed birdie chances and Mickelson rolled in a four-foot putt to take the unlikely win.

?I don?t really know what to say,? said Mickelson. ?I can?t really believe I am sitting here as the champion. I was leading by a lot, looked like I had control, then I had six penalty shots, ended up two back with three to play and then ended up in a play-off!?

-10* P Mickelson (US), R Fisher (Eng), L Westwood (Eng)

-9 K Stadler (US)

-8 P Harrington (Ire), V Singh (Fij)

-7 S Webster (Eng)

*Mickelson wins at first play-off hole