(CNN) -- Na Yeon Choi of South Korea survived a rollercoaster final round to claim her maiden victory on the LPGA Tour at the Samsung World Championship in California.
Choi kept her nerve to win her maiden title in dramatic style.
Overnight leader Choi stretched her lead to seven shots with an early burst but saw her advantage disappear and came to the final hole one shot adrift of Ai Miyazato of Japan.
But Miyazato made a hash of the par-five 18th as she hit her second into the water, while Choi found the green with two fine shots.
Miyazato chipped close, but missed her par putt, leaving Choi to sink a tricky five-footer for birdie and a one-shot win.
It was a relief after a series of near-misses and her last round drama.
"I can't believe that I won," Choi told reporters.
"Throughout the second half I thought I was going to lose it again."
Her one-under 71 gave her a 16-under total of 272 at Torrey Pines, with Miyazato carding a 69 for 273.
South Korea's Jiyai Shin was a distant third on 277.
Choi had a two-shot lead going into the final round and two birdies and an eagle in her first six holes saw her lead stretch to its maximum.
But a run of three bogeys from the ninth and a further hiccup at the 14th saw her lead surrendered to the steadier Miyazato.
Choi, who had charged into the lead with a superb nine-under 63 in the third round, admitted the jitters had nearly got the better of her again.
"I was so nervous," she said.
"It was easy, now I look back at it," Choi said. "But it was really difficult when I was doing it."
The $1 million tournament is contested by the leading 20 players in the world and is in its 29th year.