Gerina Piller, chasing her first LPGA title, fired a second-round 68 on Friday to maintain a one-shot lead after two rounds of the Marathon Classic in Ohio.
Piller had four birdies and a bogey in her three-under effort and her 11-under total of 131 put her one stroke in front of South Korean Kim In-Kyung, Taiwan's Chen Pei-Yun and Americans Lexi Thompson and Nelly Korda.
Piller, who seized the tournament lead with an eight-under 63 on Thursday, teed off on 10 and opened with six pars before a birdie at 16.
She followed her lone bogey of the day at the par-three second with three straight birdies.
"I felt like I played great," Piller said. "I missed some birdie opportunities, but I made some longer putts today. Ball striking feels great. Putting feels great.
"It was just a matter of staying patient and just letting the results come," said Piller, whose 34 top-10 results include four second-place finishes.
"It's only Friday, so I wouldn't put the cart before the horse, but to get that first win I think would be really special, no matter where it is," Piller said. "I'm just going to try to focus on the process, and the result will take care of itself."
Korda seized her share of second place with a seven-under 64 that included three birdies to end her round.
"I actually only hit one bad drive today," said Korda, who made six of her nine birdies on the back nine. "The key on this golf course is to hit as many fairways as possible, and I was doing that today, and I had short wedges into the greens, so whenever you have that, it makes it a little easier."
Her storming afternoon effort put her at 10-under 132. Thompson carded a 65 to reach 10-under while Kim posted a 67 and Chien a 68.
India's Aditi Ashok, who added the tournament to her schedule at the last minute in a bid to qualify for the Women's British Open, followed up a first-round 65 with a 68 for sole possession of sixth place on 133.
Newly crowned US Women's Open champion Park Sung-Hyun, who started the day one stroke behind Piller, carded a 70 to head a group on 134 that also included fellow South Korean Chella Choi and Americans Brittany Lincicome and Laura Diaz.