Australian golf ace Minjee Lee has lost the lead in the race for LPGA player-of-the-year honours after New Zealand's Lydia Ko took out the Ladies BMW Championship in Korea.

Ko roared home with a final-round seven-under-par 65 to storm to a four-stroke victory over American Andrea Lee (69) after finishing 21 under for the tournament.

The resurgent former world No.1 bagged eight birdies to leave the field in her wake, with Koreans Hye-Jin Choi (68) and Hyo-Joo Kim (68) and American Lilia Vu (69) sharing third at 16 under.

Lee entered the third-last event of the LPGA Tour season with a 29-point advantage over Lee in the player-of-the-year standings.

But Ko has nudged a point ahead of the West Australian after collecting 30 points for her second win of the year.

With only the top-10 finishers earning player-of-the-year points, Lee received nothing for tying for 51st at one under after closing with a 71.

Hannah Green (69) was the best-placed Australian, sharing 10th at 10 under for her sixth top-10 of the year.

Steph Kyriacou (74) was equal 19th at seven under.

Thai teenager Atthaya Thitikul entered the final round with a one-shot lead and would have vaulted to the top of the player-of-the-year standings had she won.

Instead, Thitikul disappointed with a two-over 74 on Sunday to settle for outright sixth, a distant eight shots adrift of Ko.

The 19-year-old rookie-of-the-year shoe-in still made up some ground with two events remaining before all the awards are decided.

Players pick up 30 points for a tournament win, 12 for second, nine for third and so forth down to one point for finishing 10th.

The second-ranked Thitikul, third-ranked Lee and fourth-ranked Ko also remain in the hunt to usurp Jin Young Ko as world No.1 by year's end.

Whatever transpires, Lee has already secured the Annika Major Award as the season's best-performed player in golf's four women's majors after winning the US Open and finishing joint runner-up at the US LPGA Championship.