WORLD No. 4 Stacy Lewis stormed to the top of the HSBC Women's Champions standings after a thrilling second round at the Sentosa Golf Club on Friday.

The American fired a six-under 66 for a 133 total, giving her a two-stroke lead over a chasing pack of six players that include US Open winner Choi Na Yeon of Korea and Thai prodigy Ariya Jutanugarn.

"I feel a lot more comfortable with my putter. The biggest thing for me is to stay patient and not try to force any shots, and see where that takes me," said Lewis, 28, who is looking for her sixth LPGA Tour title.

Singapore's Christabel Goh signed for a 78 (158 total) to stay in last spot among the 61-strong field.

Defending champion Angela Stanford also struggled, carding a 76 for the second straight day that left her second from bottom.

The US$1.4 million (S$1.74 million) tournament runs through Sunday at the Serapong course.