South Korea's Ko Jin-young fired nine birdies in a sensational nine-under par 63 on Sunday to win the LPGA Tour Championship and pip Nelly Korda for Player of the Year honors.
Ko's second straight victory in the season finale was her fifth LPGA title of the year.
The $1.5 million winner's prize pushed her past $9 million in career earnings.
"I don't know what happened out there," said Ko, who has battled a nagging left wrist injury that limited her practice for much of the season. "This week was amazing."
Ko and Korda had swapped the number one ranking all season, but it was American Korda who came into the event at Tiburon Golf Club in Naples, Florida, atop the rankings and with a slim lead in the Player of the Year race.
Both were among a four-way tie for the lead through 54 holes, and Korda's tie for fifth wasn't enough to secure the year-end award.
Japan's Nasa Hataoka, who also shared the overnight lead, fired an eight-under par 64 to finish second on 266.
It was four strokes back to Mina Harigae and overnight co-leader Celine Boutier on 270, with Korda heading a trio on 271.
Ko opened with three birdies in her first four holes, rolling in a long birdie putt at the first to jumpstart her day.
She drained a 30-footer for her sixth birdie of the day at the ninth, seizing a four-shot lead.
Hataoka sliced into her lead with birdies at the seventh, ninth, 10th and 11th.
But Ko rolled in another long birdie putt at the 11th and birdied the 13th for a three-shot edge.
Hataoka kept pressing, with birdies at 15, 17 and 18, but Ko's final birdie at the 17th was enough to clinch the victory.
Ko, 26, now has 12 LPGA titles, and her latest was plenty impressive.
- The Ko Show -
Sunday's round was the third straight in which she hit all 18 greens in regulation.
"It was definitely the Jin-young Ko Show today," said Korda, the Olympic gold medallist who was also going for a fifth LPGA win of the season.
Korda finished with four birdies and a bogey in her three-under effort that left her tied with Australian Minjee Lee and American Megan Khang.
"It was really cool to witness," added Korda. "I wish I could have given it a better run, but in all I think I had a great year.
"So I'm just going to kind of look back on that and enjoy it. Today, she just played amazing golf. There is not much you can do, just sit back and watch, honestly."
Ko, meanwhile, was going to savor another season-ending victory and her second Player of the Year award in three years, one that she said all week she was unlikely to wrest from Korda.
"I tried to play aggressive and I got it and I'm so happy," she said. "She got gold medal and she had major. She had three more wins this year. She hits it straight and too far and putting so good.
"I was a little bit more lucky than her, so I got this."