American Brittany Lang earned her first LPGA Tour victory, winning the Manulife Financial Classic by making birdie on the par-five 18th hole three consecutive times in a playoff.
Lang on Sunday held off a wave of South Korean contenders in the playoff after shooting a four-under 67 in regulation to reach 16-under 268.
"I just tried to stay down in the putt and have nice tempo," Lang said. "I haven't been in this position much. I'm just trying to learn.
"I can't believe I finally won. I've had my chances and I still can't believe I did it."
She edged out South Koreans Seo Hee-kyung, Chella Choi and Inbee Park at the Grey Silo Golf Course.
Choi was knocked out on the first extra hole, third-round leader Park was eliminated on the second hole, setting the stage for a head-to-head battle between Lang and Seo. Lang rolled in a five-foot putt for the win. Four of the top six and six of the top 13 finishers Sunday were from South Korea.
The birdie made amends for a shorter putt that Lang missed on the 18th hole in regulation that would have clinched the tournament for her.
Choi closed with a 63 on Sunday, Park a 69 and Seo a 67 to get to 16-under.
Reigning US Women's Open champion Ryu So-yeon and American Stacy Lewis both fired seven-under 64s on Sunday to finish in a tie for fifth at 15-under. Lewis is a two-time winner this season.
Playing partners Lang, Seo and Park all settled for pars on 18 to set up the playoff.