Talented Thai golfer Patty Tavatanakit broke free of the pack with a six-under third round of 66 in sweltering conditions to lead the $1.7 million LPGA Thailand by three shots on Saturday.
Sweden's Madelene Sagstrom was alone in second, three shots behind on 13-under, after a steady third-round 69 at the Siam Country Club Pattaya.
South Koreans Choi Hye-jin and Kim Hyo-joo and Denmark's Emily Kristine Pedersen were tied in third place on 12-under 204.
Choi and Pedersen both fired seven-under 65s, the Korean's topsy-turvy round including seven birdies, an eagle and two bogeys. Her compatriot Kim shot a more measured 69.
Tavatanakit is steadily building momentum after her win at the Aramco Saudi Ladies International last week, her first title since 2021.
Ranked 43rd in the world, the 24-year-old had a stellar start, carding four birdies and an eagle in the first nine holes on Saturday.
She sits on 16-under 200, three shots clear going into Sunday's final round, and said she was feeling confident despite the heat.
"I'm really proud of my performance today. It's getting very tiring, exhausting in the heat," she said.
"I'm just going to have fun, stay present, and be very, very busy with my process."
Pedersen, 27, had trouble with her drives on the front nine before settling down with a round that included eight birdies and a single bogey.
"I want to keep the foot on the gas," she said, while also praising Tavatanakit's round.
"But I do believe I can play like that myself and hopefully I can do that tomorrow," she said.
Thai amateur Suvichaya Vinijchaitham also crept up on the leaders with a five-under 67, her best of the tournament, for a share of sixth place on 205.
She is alongside compatriot and 2021 winner Ariya Jutanugarn, Canada's Brooke Henderson, Switzerland's Albane Valenzuela and Friday's leader Kim Sei-young of South Korea.
Ariya, ranked 52nd in the world, said she was just warming up.
"I think this week my putting starts to get better," the 28-year-old said.