England\'s Lee Westwood will face stiff competition from some of the world\'s top players when he defends his Thailand Golf Championship title in December. Bubba Watson, the 2012 Masters champion who is ranked eighth in the world, and 2012 World Golf Championship winner Hunter Mahan, ranked 19th, will be among those trying to secure the Asian Tour crown. Three other Major champions -- Northern Ireland\'s Darren Clarke (2011 Open champion), South Africans Charl Schwartzel (2011 Masters champion) and Louis Oosthuizen (2010 Open champion) -- have committed to play in this year\'s $1 million event, the Asian Tour said Wednesday. Spain\'s Sergio Garcia, ranked 17th, who last month won the USPGA Tour\'s Wyndham Championship, will also be a strong contender for the title judging by recent form. The Asian challenge will be spearheaded by Thongchai Jaidee, a three-time Asian Tour number one who played in the Open Championship and PGA Championship this year. Thongchai, regarded as one of Asia\'s greatest players, has won five European Tour events, including the Wales Open this year, and has earned 13 Asian Tour titles, a record he shares with veteran Thaworn Wiratchant, who will also be contesting at the Amata Spring Country Club event, from December 6 to 9. Westwood, ranked 4th in the world, won the full-field Asian Tour title in majestic fashion last year, storming to a seven-shot victory, with a 12-under-par 60, narrowly missing out on the magical 59, which has never been shot on the Tour. \"It was one of the best rounds I\'ve ever played,\" said Westwood. \"I was just on a roll. I hit a lot of fairways and my putting was good. \"Asian courses seem to suit me. I always feel comfortable.\"