Thailand's Patty Tavatanakit shot a third-round 67 on Saturday to take a commanding five-shot lead into the final round of the ANA Inspiration major in Rancho Mirage, California, US.
Tavatanakit, who entered the day with a one-stroke lead, sits at 14 under for the tourney.
Ally Ewing (66) and South Korea's Mirim Lee (68) are tied for second at 9 under. Shanshan Feng of China sits alone in fourth at 8 under after a 72.
Inbee Park (70) of South Korea and England's Charley Hull (71) are tied for fifth but enter Sunday's final round seven shots back.
Tavatanakit, 21, is poised to earn her first career LPGA victory after carding three birdies to start her round. She finished the day with seven against two bogeys.
She was later asked how she would keep her focus with such a large lead.
"You know, today I'm going to leave it behind. It's a great day, acknowledged it, and it's in the past now," she said. "All I can think about is what can I do (Sunday), what can I improve from today's round? I was getting a little tired at the end. What can I do to keep my energy level up throughout the day (Sunday)? That's going to be my goal."
Tavatanakit will be paired with Ewing, who finished with a better round by one stroke with a clean round of six birdies. It was a career-low round and the low round of the tournament.
"Obviously a great start with three birdies on 1, 2 and 3. That really just gave me a lot of good momentum throughout the day. I just gave myself a lot of looks for birdie," Ewing said. "I missed few putts even inside 10 feet for birdie, so I drove the ball great and I struck the ball great, which is crucial in this major, and to give yourself as many looks as you can."