South Korea's Choi Hye-jin birdied her last two holes to take a one-shot lead on seven-under par 64 at the LPGA Dana Open in Sylvania, Ohio, on Thursday.
The 24-year-old, who is chasing a first LPGA tour victory, was one shot in front of India's Aditi Ashok and China's Lin Xiyu, Ashok firing six birdies without a bogey in her six-under 65 while Lin posted eight birdies and two bogeys.
"It was a really great day," said Choi, who teed off on 10 and didn't pick up her first birdie until the 17th.
That launched a run of four straight birdies. She added another at the fifth before closing with birdies at the eighth and ninth to move ahead of early pacesetters Ashok and Lin.
She said an adjustment to her putting, after she struggled in the pro-am on Wednesday, made the difference.
"I hit it too hard yesterday," she said, adding that she tried to soften her stroke and focus on her tempo on the greens.
"It worked," she said. "So it's good."
Lin, the highest-ranked player in the field at 15 in the world, holed out from bunkers twice as she played her way into contention for a first LPGA title.
The first time was at the 15th. The second was at the first hole – her 10th, where she said she was just trying to get her ball on the green but watched it bounce just short and rattle into the cup.
"I'm like OK, that's the only way I can stop it," she said.
"Almost like two impossible shots to hole out, that's a bit of luck," added Lin, who is using the tournament as a final tuneup for her third Olympics in Paris.
Lin played alongside Ashok and defending champion Linn Grant of Sweden, who launched her title defense with a 67.
Thailand's Chanettee Wannasaen and Natthakritta Vongtaveelap and South Africa's Paula Reto shared fourth on 66.