Sung Hyun Park made her first LPGA Tour title a major as she won the US Women's Open at Trump National.
The 23-year-old Korean shot a closing five-under-par 67 to finish on 11 under in Bedminster, New Jersey.
That was two ahead of compatriot Hye Jin Choi (71), who missed out on becoming the first amateur major champion for 50 years after finding water at the 16th.
Two more Koreans, Mi Jung Hur (68) and So Yeon Ryu (70), finished tied for third on seven under, with China's Shanshan Feng (75) - who led after each of the first three rounds - finishing in a tie for fifth after running up a triple-bogey eight on the final hole.
Park, Choi and Feng did battle throughout the final round, but it was Park who held her nerve over the closing holes.
Feng looked to be in control when she birdied the 10th from close range and Choi missed an eight footer for par.
However, Park tied for the lead with a 20-foot gain on the 15th.
The 17-year-old Choi got up-and-down at the 15th to retain a share of the lead but saw her hopes sink when her tee shot to the 16th found water and she ran up a double-bogey five.
Park went two clear with a birdie from six feet at the 17th and got up-and-down for par at the last.
That left Feng needing an eagle at the last to force a play-off, but her triple bogey sent her tumbling down the leaderboard.
"I did not have the best first and second rounds," Park told the LPGA website through a translator.
"I wanted to believe in myself again for the final two rounds and I did."
England's Charley Hull finished tied for 21st after a closing 73.