LPGA Hall of Famer Park In-bee of South Korea fired a three-under par 69 and stretched her lead to five strokes after Saturday's third round of the LPGA Kia Classic.
Park, a seven-time major champion seeking her 21st career LPGA title, stood on 12-under 204 after 36 holes at Aviara, north of San Diego.
"I think it's just going to be the same game plan that I have done for last three days, and hopefully things work out just exactly the same as what we have done for three days," Park said. "Just trying to hit a lot of fairways and greens and hopefully the putts will fall."
After leading by only a single stroke when the day began, Park seized command as rivals stumbled, leaving England's Mel Reid, Australian Minjee Lee and South Korean Hur Mi-jung sharing second on 209.
"I'm going to have to do something special to get it done," Reid said.
"The game plan is to play aggressive and there's nothing to lose. I'm going to try and get as close as I can to In-bee, but she's an unbelievable golfer and she's going to be hard to beat. She doesn't make any mistakes.
"She's one of the best players to ever play our game. You're going to have to probably shoot 6- or 7-under to even have a chance of winning."
Sweden's Madelene Sagstrom fired a 64 to share fifth on 210 with South Korean Ko Jin-young and American Lexi Thompson.
It's Park's first event of the year as she prepares for next week's ANA Inspiration, the LPGA's first major tournament of 2021, at Rancho Mirage, California.
"I'm really getting the good feel of it," Park said. "I played well last three days."
World number four Park birdied the par-5 fifth and par-4 seventh and responded to a bogey at the par-3 11th with a birdie at the par-4 13th, hitting a 9-iron to 12 feet and sinking the putt.
"I was just going through that a little bit of a rough time, was going down a little bit," Park said. "Then No. 13 birdie was a big turnaround and I was able to finish well after that."
Park added a five-foot birdie putt at the par-5 17th and got up and down for par at 18 on a day when four tees were moved up and the course played about 300 yards shorter than Friday.
"They made the course very reachable and I couldn't take advantage of those holes, but I played the rest of the holes good, so I'm happy with that," Park said.