Seventeen-year-old amateur Ssu-Chi Cheng of Taiwan shot a 66 and was in a four-way tie for third.
So Yeon Ryu, the 2011 U.S. Women's Open winner, was on 59 watch after getting to 9 under par with eight birdies and an eagle against one bogey through 12 holes. But she parred the next four holes and bogeyed the par-3 17th. On the par-5 18th, she hit her tee shot into a hazard to the left of the fairway and missed a 5-footer for bogey, falling two shots off the lead with a 66.
Lydia Ko was five shots back after a 69.