Sei Young Kim sank a 25-foot birdie putt at the final hole to win the CME Group Tour Championship and the biggest prize in women's golf, $1.5 million, in Florida.
After leading almost the entire tournament, Kim nearly blew it before coming through in unlikely circumstances at the par-four 18th, where her downhill putt broke deliciously to the right and trickled in.
The South Korean carded two-under-par 70 to win by one stroke from England's Charley Hull, who almost stole the tournament with five birdies in the final seven holes for a 66 at Tiburon Golf Club in Naples.
Kim admitted that nerves had affected her putting down the stretch as she hit a series of poor putts while trying to not think about the record first prize.
She did not look at any leaderboards and said she was unaware the birdie putt at the last was for the win and the Race to the CME Globe title.
"I was thinking, try to make two-putt, that's my mindset," an emotional Kim said after finishing at 18-under 270 for her 10th LPGA Tour victory at the age of 26.
"It was really nervous the whole 18. It means a lot. At the beginning of year I set a goal to three times win so I'm very glad to reach that goal, most satisfied."
Kim is the fourth Korean player to reach double-digit LPGA victories, joining Pak Se-ri (25), Park In-bee (19) and Shin Ji-yai (11).
All of her 10 victories have come since 2015, and nobody on tour has won more often during this period.
Hull, barely an afterthought until her late charge, nearly gatecrashed the party with birdies at the final three holes, including a 10-footer at the last after a superb eight-iron approach shot.
The 2016 winner barely qualified to play this year and was 51st in the standings at the start of the week. Her play down the stretch belied her low ranking.
Americans Danielle Kang (65) and Nelly Korda (71) were also in contention, eventually finishing two shots behind Kim.
Kim's win capped off another dominant year for South Korean players, who have ruled women's golf for the best part of two decades.
They combined to win 15 of 32 LPGA tournaments in 2019.