Defending champion Yani Tseng carded a 66 to move two shots clear after three days of the Kraft Nabisco Championship, the LPGA's first major of the year.
It took the Taiwanese player to 12 under par ahead of Stacy Lewis, who led for the first two rounds but dropped back after a 71 on Saturday.
Tseng, seeking her fourth major title, recorded six birdies and no bogeys.
Karen Stupples and Sophie Gustafson lead European hopes but are 10 shots off the lead in a share of 10th.
American Morgan Pressel inched up two places to third after a round of 69 left her eight under.
Michelle Wie shot the same score after four birdies on the back nine and stands fourth going into the final round on six under, one ahead of Angela Stanford.
Brittany Lincicome's challenge faded as she shot a 74 and dropped from a tie for second into a tie for sixth on four under.
It was a day to forget for Jane Park, playing alongside Tseng and Lincicome, who had a double bogey seven at the ninth and dropped back to two under.