Published: Nov 06, 2011 8:51 AM EST
Updated: Nov 07, 2011 7:30 AM EST

SHANGHAI (AP) - Martin Kaymer made nine birdies over his last 12 holes Sunday and closed with a 9-under 63 to win the HSBC Champions for the biggest comeback ever in a World Golf Championship.

Starting the final round five shots behind Fredrik Jacobson, with a host of stars around him, Kaymer ran off four straight birdies to start the back nine at Sheshan International. The German finally caught Jacobson with a birdie on the 13th, and then poured it on with key birdies on the final two holes.

Kaymer delivered the lowest closing round by a WGC winner since the series began in 1999, topping the 64 by Hunter Mahan last year at the Bridgestone Invitational.

The former PGA champion hasn't found golf to be this easy since he shot a 59 his first year as a pro on a mini-tour in Germany, when he was 14 under over his last 16 holes.

"I just played really good golf, and I'm glad that it came together," Kaymer said. "The last few weeks, I played good golf, but it has not happened yet. And this week, it was nice that it happened here, the World Golf Championship event."

Kaymer is the 10th player to win a WGC and a major championship.

Adam Scott, hounded by questions over caddie Steve Williams' racial slur against former boss Tiger Woods, got within two shots of the lead early in the round until making two soft bogeys and never recovering. He closed with a 73 and was eight shots behind.

Jacobson led by as many as three shots until a long three-putt bogey on the par-5 eighth. As Kaymer made his charge, the Swede came to life with birdies on the 12th and 14th to stay tied. Jacobson's hopes ended, however, when he pulled his tee shot into the rough left of the par-3 17th and failed to get par. He shot 71 and finished three shots behind.

"I wish I could have made maybe a couple of more putts along the way to really get a little bit of a cushion and put a little bit more pressure on Martin coming down the stretch," Jacobson said. "I gave it my everything, and overall, a great week."

Graeme McDowell closed with two birdies for a 67 to finish alone in third, quite a turnaround from last week in the Andalucia Masters when he failed to break 80 over the last two rounds at Valderrama.

Rory McIlroy made a short birdie on the par-5 18th that gave him a 69 and was significant for one other reason. With a three-way tie for fourth, he moved past Lee Westwood to the No. 2 ranking. Westwood, playing in the same group, shot 40 on the front nine and closed with a 74 to tie for 13th.

It was the second win of the year for Kaymer, who moves to No. 4.

He won his first tournament of the year at Abu Dhabi and became the top-ranked player at the end of February, holding the spot for eight weeks. Kaymer said he struggled with the attention of being No. 1, and the face of golf in Germany, and now was looking ahead.

"It was an OK year," Kaymer said. "But now it's a good year."

Europe now occupies the first four positions in the world ranking, starting with Luke Donald at No. 1. Donald did not play in the HSBC Champions because his wife is expecting their second child. He remains the favorite for PGA Tour player of the year, however, as PGA champion Keegan Bradley had a 72-72 weekend and failed in his bid for a third victory this year.

Kaymer finished at 20-under 268 and earned $1.2 million.