Stacy Lewis made six birdies to shoot a 66 and take a two-stroke lead after Friday's second round of the HSBC Women's Champions.
Lewis, the reigning LPGA Player of the Year, was at 11-under 133 overall.
She led a pack of six players in second place at 9-under: Ariya Jutanugarn (66), Na Yeon Choi (66), Chella Choi (67), Paula Creamer (67), Sun Young Yoon (68) and overnight leader Azahara Munoz (70).
Top-ranked Yani Tseng stumbled with a double bogey on the par-5 4th hole and shot a 73. She was in a share of 21st place at 3 under.
Lewis has started this season in the form that saw her win four titles last year. She also held the second-round lead last weekend in Thailand but finished third.