Mi Hyang Lee of South Korea fired a course-record nine-under-par 63 to win the Women's New Zealand Open by one shot from local hope defending champion Lydia Ko.
World No 256 Lee, whose best finish last year was a tie for 19th place at the Evian Championship, carded an eagle and seven birdies to surge up 20 places to the top of the leaderboard with a nine-under total of 207.
World No 4 Ko, 16, had a long birdie putt on the final green for a chance to force a play-off in the 54-hole event at the Clearwater course in Christchurch.
But in front of a huge home gallery, she left her effort short as she closed with a two-under 70.
Ko and her playing partners - Americans Beth Allen and Anya Alvarez - all stood on the final tee one shot behind Lee.
Both Allen and overnight leader Alvarez bogeyed the 18th after their approaches missed the green to fall back into a tie for third place with South Korean Seon Woo Bae.
England's Charley Hull finished in joint-11th place - six behind Lee - after closing with a one-under 71.