South Korea's Jang Jeong maintained her grip at the US$1.3 million LPGA Fields Open on Friday, carding a 68 to keep a one-shot lead over compatriot Kim Song-hee.
Jang's four-under second-round effort gave her a 12-under total of 132.
One day after she nabbed nine birdies against just one bogey, Jang notched seven birdies and three bogeys.
Kim, meanwhile, shot up the leaderboard with a course-record 64 for 133. Her round included eight birdies with no bogeys.
US player Paula Creamer was two shots back after a 68 for 134, while Australian Lindsey Wright carded a 66 for 135.
Jang opened with a birdie at the par-five first, but gave the shot back with a bogey at the third.
She responded with birdies at the fourth, sixth and eighth, before back-to-back bogeys at nine and 10 set her back.
She rallied again with birdies at 11, 13 and 14.
"I was a little disappointed with my chipping," she said. "The chipping was really hard today on the green. I didn't make the easy pars.
"So I was a little disappointed with my short game today. Putting is going really well, so I think I'm going to be good position though."
Sweden's Annika Sorenstam, seeking to become the first player since LPGA founder Marilynn Smith in 1966 to win back-to-back official money events to open a season, was among a quartet of players tied for fifth on 136. Sorenstam, who is in search of her 71st career title, had a bogey-free 66.
Angela Stanford (69), Finland's Minea Blomqvist (65) and Kelli Kuehne (69) were tied with Sorenstam.
Michelle Wie, who was plagued by a wrist injury for most of last season, shot a one-over 73 to fall into a tie for 41st place.
Jang was to play in the last group with Kim in yesterday's final round.
"I never played with her before, and I actually never heard her name before," Jang said. "I know that last year was her rookie year. We're eight years apart, so I never played junior tournaments together, but I heard she's a really good, strong player."
"I didn't miss a lot of shots," said Kim, whose longest birdie putt was 30 feet, at the par-four seventh.
That was one of her five birdies on the front nine, and she added three more coming in, including an 18-footer at the 17th.