Ji-Yai Shin held off Karrie Webb and Paula Creamer to win the LPGA's season-ending ADT Championship by one stroke with a two-under-par 70.
The 20-year-old South Korean shared fifth after the third round but all prior scores were wiped out for the eight-woman Sunday shootout in Florida.
Shin, the reigning British Women's Open champion, birdied the second and third holes to but bogied the seventh.
A bogey at the 15th might have cost Shin but she held on for the $1m prize.
In doing so Shin became the first non-LPGA Tour member to triumph three times on the US circuit.
Shin, who will join the LPGA Tour next year, plays mainly in Asia.
Webb, who trailed by two strokes with two holes to play, increased the pressure with a birdie at the par four 18th but Shin holed for par to dash the Australian's hopes.
"I gave myself a chance," said Webb. "Making it to Sunday was the minimum goal for the week, and today I played very solidly.
"I just probably needed a couple more putts to go in. I'm just glad I made Ji-Yai think about it on the last hole."
America's Creamer, a questionable starter after suffering severe abdominal pain on Saturday night, and South Korean Seon Hwa Lee shared third on 74, one stroke ahead of Ji Eun-Hee.
"I gave it all I had," said Creamer. "I tried as hard as I possibly could. I wasn't going to quit."
Angela Stanford was sixth after firing a 78, one stroke better than Suzann Pettersen and Jeong Jang.
Creamer, second on the money list entering the event, would have passed top-ranked Lorena Ochoa of Mexico to win the season money title had she won.
No US-born player has won the money crown since Betsy King in 1993.
Ochoa was eliminated Saturday, the same day she was named the LPGA Player of the Year for the third season in a row and a day after Sweden's Annika Sorenstam, playing in her final LPGA event, was also ousted.
Pettersen, seeking her first victory over the season, led after the third round but her advantage was erased under the playoff-style rules.
She had four bogeys in the first five holes Sunday and was never a threat.
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