Thailand's Patty Tavatanakit steered a steady course to hold off charging Lydia Ko and win the ANA Inspiration on Sunday, making her first LPGA title a major championship.
Patty, 21, started the day with a five-shot lead and fired a four-under par 68 at Mission Hills in Rancho Mirage, California.
Her 18-under total of 270 put her two strokes in front of New Zealand's former world number one Ko -- who stormed from eight adrift with a sensational 10-under 62 for 272.
Four players shared third on 277: South Korean Kim Sei-young, American Nelly Korda, Denmark's Nanna Koerstz Madsen and China's Feng Shanshan.
"I had no idea," Patty said of Ko's spectacular round, which matched the tournament record established by Mexican great Lorena Ochoa in the first round in 2006.
"I just played my own game, didn't look at the leaderboard at all ... I just wanted to play my own game and I did -- I did a really good job of that today."
Patty, who played collegiate golf at the University of Southern California at Los Angeles, padded her overnight cushion with a chip-in eagle at the par-five second and picked up another stroke at the eighth.
She was unable to take advantage of the par-five 11th, but left herself less than two feet for a birdie at the 12th.
She needed a few par saves on the back, her eight-foot par putt at the 15th circling the rim of the cup before dropping in. She missed the green at 17 but chipped to within inches.
Patty said she just told herself to "keep hitting good shots."
"My putts were rolling well, just didn't read it well today. Overall I feel like I stuck to my game plan, I overcame the adversity out there."
Patty said she didn't get much sleep on Saturday night, and felt nervous in the early going.
"It was tough mentally and I feel like it was a lot going on and I handled it pretty well."
Patty, still designated an LPGA rookie after the coronavirus pandemic disrupted her first season on tour, is the first rookie to win the ANA Inspiration since Juli Inkster in 1984.
She's the fourth wire-to-wire winner, with no shared overnight leads, and the first since Australian Karrie Webb in 2000.
"It feels great to be a major champion. It still hasn't really sunk in yet the fact that I'm like -- I just turned 21 six months ago and now I'm a major champion in my rookie year. Just crazy."
- Confident Ko -
Ko, meanwhile, had surged up the board, picking up three shots in the first two holes with an opening birdie and an eagle at the second. Birdies followed at the fourth, sixth, seventh and ninth.
"I don't think there wasn't an exact moment where I felt like 'Ok, this is going to be a good one,'" Ko said. "You just have to focus until that last putt drops on that last hole."
The pace slowed somewhat on the back nine, where birdies at the 10th, 11th and 15th moved her within two strokes.
Ko, who counts two majors among her 15 LPGA victories couldn't find another birdie in the last three holes and remains in search of her first victory since the 2018 Mediheal Championship.
"I'm just happy that I got to finish strong in this event and be in contention and be just right up there," Ko said. "It gives me a lot of confidence to say, 'Hey, we're trending in the right direction.'"
But, she added: "It's more important just focusing on the present and not get carried away about what's going to happen in the future and what happened in the past."