Lorena Ochoa shot a 3-under-par 69 on Friday to surge past Becky Morgan and into the second-round lead at the Rochester LPGA.
Ochoa, who began the day three shots behind Morgan, finished her round in a steady rain at 8-under 136.
Morgan, who had a sizzling 8-under 64 on Thursday, faltered late and shot a 74 to finish tied for second with Maria Hjorth (68).
Rookie Paula Creamer, who finished the first round with back-to-back bogeys after injuring her left wrist, is alone in fourth after following her opening round 71 with a 68.
Rain fell throughout the opening round, and under the soggy conditions at Locust Hill Country Club the players were allowed to lift, clean and place on Friday. Still, among the top 14 players, only Ochoa, Mi Hyun Kim (66) and Creamer broke 70.
"I took advantage of the opportunities and finished strong," said Ochoa, a runner-up three times this year and third on the money list. "But I don't know how I shot so good. It's weird. Sometimes, things go your way."
They went Creamer's way, too. Creamer birdied three of her first four holes before bogeying the par-3 15th hole. Her second shot at 18 landed in the bleachers bordering the right side of the green.
After getting a free drop into the thick rough, she chipped in from 25 yards for birdie.