Stephanie Meadow carded a six-over 78 to plunge down the leaderboard after day two of the BMW Ladies Championship at Seowon Valley Country Club, South Korea.
The Northern Irish golfer had come into the second round off the back of a bogey-free 67 on Thursday.
But Friday proved a difficult one as the previous day's gains were quickly wiped out on a front nine which saw her double bogey both the fourth and eighth as well as further dropped shots on two and nine.
The back nine was more steady but she stays one over in a tie for 57th, 12 shots off the lead, after a bogey on 15 followed by a birdie on 17.
At the top of the leaderboard, Australia's Minjee Lee battled swirling winds to grab a two-stroke lead ahead of the weekend's final two rounds.
Moving to 11-under with a three-under 69 that featured four birdies and one bogey, Lee leads at the midway point for the 11th time in her LPGA Tour career. It's her lowest 36-hole score since winning the 2022 US Women's Open.
First-round leader Ashleigh Buhai of South Africa (73) and Alison Lee (72) are two shots back at nine-under entering the weekend.
Minjee Lee birdied both par-5 holes on the back nine at 11 and 15, reaching the green in two at the latter. She capped her round with another birdie at the 18th and the 27-year-old said it would be special to win in the country where both her parents were born.
"I have a really deep heritage here. So I always love coming back and playing," she said.
"Being at the top of the leaderboard is always nice, and being in contention is always my goal. So hopefully I can have a great weekend."
Buhai was at 13-under through 12 holes before closing with four bogeys on the final six holes, including three in a row from 13 to 15.
"I think that is one of the toughest days I've ever had on a golf course in terms of the wind switching," Buhai said. "I've never played any round where the wind just switched that much."
Defending champion Lydia Ko of Australia (69) and South Koreans Jeongeun Lee6 (68) and Hae Ran Ryu (71) are tied for fourth and three shots back of the leader.
Last week's Buick LPGA Shanghai winner Angel Yin is tied with China's Yan Liu at seven under, with Nelly Korda, France's Celine Boutier and England's Jodi Ewart Shadoff sitting in a tie for ninth at six under.
Rolex Rankings No. 1 Lilia Vu closed with a double bogey on No. 18 to settle for a second-round 76 and a tie for 57th at one over.
Additional reporting: Reuters
