American Jessica Korda fired a seven-under-par 67 in the final round to snatch a one-shot victory in the Airbus LPGA Classic.
The 21-year-old began the day in a tie for fourth place and picked up only one birdie on the front nine on The Crossings course at Magnolia Grove in Alabama.
However, six birdies on the back nine sent her charging to the top of the leaderboard on 20-under 268.
Korda's decisive move came with three successive birdies from the 14th before a birdie at the 18th - where she holed a 15-foot putt - sealed her third LPGA Tour victory.
Sweden's Anna Nordqvist had to settle for second place on 19 under following a costly front nine on which she sandwiched one birdie with two bogeys on the first and ninth.
She recovered with four birdies on the back nine, including one at the 18th, but her three-under 69 left her just short.
The leading players were tightly packed for much of the round before Korda broke free in the closing stages and English teenager Charley Hull (67) and Scottish veteran Catriona Matthew (69) were both firmly in contention.
The pair eventually finished in a tie for third with American Michelle Wie (67) on 18 under.
Jenny Shin of South Korea (67) was sixth on 17 under, with Jodi Ewart Shadoff (68) of England one shot further back in joint-seventh alongside American Lexi Thompson (66) and Korean Eun-Hee Ji (68).
American Stacy Lewis carded a 71 and finished joint-10th on 15 under, meaning she missed out on the top-three finish required to overtake South Korea's Inbee Park as world No 1.