SYLVANIA, Ohio (AP) Gerina Piller followed her opening 8-under 63 with a 68 on Friday to maintain a one-stroke in the Marathon Classic.
Winless on the LPGA Tour, Piller had four birdies and a bogey at Highland Meadows to reach 11-under 131.
U.S. Solheim Cup teammate Lexi Thompson had a 65 to move into a tie for second with fellow American Nelly Korda, South Korea's In-Kyung Kim and Taiwan's Peiyun Chien. Korda had a 64, Kim shot 67, and Chien 68.
India's Aditi Ashok was 9 under after a 68. Sung Hyun Park, the U.S. Women's Open winner Trump National in New Jersey, had a 70 to join fellow South Korean player Chella Choi (67) and Americans Brittany Lincicome (67) and Laura Diaz (67) at 8 under.
Stacy Lewis, her U.S. Women's Open chances ruined by a third-round meltdown, was 2 under after a 71.
Lydia Ko, winless since her victory last year at Highland Meadows, had a 68 to reach 1 under. She also won the 2014 event.
Canadian Brooke Henderson missed her second cut of the season, shooting 70-75.