American Paula Creamer won the Samsung World Championship at Half Moon Bay in California, finishing one shot ahead of South Korea's Song-Hee Kim.
The 22-year-old carded a final round 69 as she birdied the second, fifth and 15th holes to finish nine under par.
Kim hit six birdies in a round of 68, but bogeys at the ninth and 11th put paid to her hopes of victory.
Suzann Pettersen, Lorena Ochoa, Juli Inkster and Angela Stanford were tied for third on seven under.
Mexico's world number one Ochoa, who was seeking her third consecutive win in the tournament, failed to improve on her overnight position of tied for third.
Standford, who was second going into Sunday's final round, was two under for the day, while Pettersen and Inkster each carded 68 to move up the leaderboard.
Creamer's victory was her eighth on the LPGA Tour and her fourth this year.
"That is big win for myself," she said. "I put so much pressure on myself every time I come here and to finally have one, it feels really good. I'm very excited."
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