Westwood notched a six-under 66 on day two to move to 13-under at the tournament's half-way point, four strokes clear of Belgium's Nicolas Colsaerts and Antonio Lascuna of the Philippines.
Westwood, who managed a seventh-place finish at the Masters on Sunday, stumbled out of the blocks in Malaysia with a bogey on his first hole of the day.
The talented Anirban Lahiri will be amongst the top stars from the Asian Tour who will feature in the $2.75 million Malaysian Open which starts at the Kuala Lumpur Golf and Country Club on Thursday.
Thongchai Jaidee, who has won 13 times on the Asian Tour, and is a five-time winner on European Tour, and a three-time Asia No.1, made the cut at the Masters for the first time in three appearances.
Bubba Watson, a growing presence in the golf world with a boyish mien, won his second green jacket at 35 years old.
Bubba Watson fired a three-under par 69 Sunday to finish 72 holes on eight-under 280 and take his second major title, the top prize of $1.62 million from a record $9 million purse and another green jacket.
Bubba Watson and Jordan Spieth were tied at 5-under 211 at the Augusta Masters.
Bubba Watson and Jordan Spieth ended Saturday's third round tied for the lead at five-under 211.
With a dazzling display of precision on one of golf's most intimidating layouts, 35-year-old US left-hander Bubba Watson fired a four-under par 68 to stand on seven-under 137 after 36 holes at Augusta National.
Fred Couples, the 1992 Masters winner, shared seventh on two-under par 142 after 36 holes at Augusta National, five strokes off the pace of 2012 Masters winner Bubba Watson entering the weekend.
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