Westwood, the former world No. 1, had fallen to third, but inched back up thanks to the victory in Thailand.
Luke Donald remained in first, followed by Westwood and Rory McIlroy, who dropped one. Martin Kaymer, Adam Scott, Steve Stricker, Dustin Johnson and Jason Day each remained in their places from last week.
Masters champion Charl Schwartzel rose two to ninth, while Webb Simpson and Matt Kuchar both fell a spot for Schwartzel's move. Nick Watney, Graeme McDowell, Phil Mickelson and K.J. Choi completed the top 15.
Tiger Woods fell one to No. 23.