LEE WESTWOOD won the Asian Tour's $1million Thailand Golf Championship by one shot after US Open champion Martin Kaymer and third-round leader Marcus Fraser both faltered at the finish.

Westwood bogeyed his opening two holes, but then reeled off seven birdies in a blistering 10-hole spell from the sixth to complete a superb five-under-par round of 67 for an eight-under total of 280 and the clubhouse lead.

He then watched as Australian Fraser, playing on a sponsor's invite after missing most of the year because of a wrist problem, blew the opportunity to force a play-off by making a bogey at the par four last to drop back to seven-under.

Westwood's Ryder Cup-winning team-mate Kaymer also came unstuck on the tricky closing holes at the Amata Spring Country Club, the German making his only bogey of the day on the penultimate, island green 17th to finish tied with Fraser.

"This is my last event of the year and it's nice to finish with a win and go into Christmas and start the New Year with confidence," the 41-year-old Westwood said after his 41st career victory and second Thai Golf Championship.

Fraser had started the day one ahead of India's Anirban Lahiri (73) and two clear of the former world No.1s as he went in search of his first Tour title in over four years.

Five birdies in his opening 11 holes stretched that lead to three as Lahiri fell away, but Westwood and Kaymer closed the gap with birdies after the Australian bogeyed the 12th.

Westwood made his seventh birdie of the day at 15 to leave the trio tied at eight-under and then parred the closing holes as his rivals faltered.

Lahiri endured a mixed round of seven birdies, four bogeys and two double bogeys as he finished in a share of sixth to end his bid to become Asian Tour's Order of Merit winner.

That prize went to American David Lipsky, who has an unassailable lead in the standings over the Indian with only the season ending Dubai Open to come next week.

Lahiri and Fraser were comforted by booking spots in next year's Open Championship at St Andrews with their strong finishes in Thailand.

"That would put some balm on my wounds. I've had a great year and I have a lot to look forward to," the Indian said.

Australian Scott Hend, who finished four back of Westwood in fifth, and American Jonathan Moore, who was tied sixth alongside Lahiri, took the other two places on offer for St Andrews.