The 28-year-old from Mississippi held off Danielle Kang by a stroke on the Great Waters Course, closing with a 3-under 69 for a 16-under 272 total.

Katherine Kirk finished in a share of sixth place at 11-under after a final round 2-under-par 70 to be the best of the Australian contingent.

McDonald birdied the first three holes on the back nine, dropped a stroke on 14, birdied 16, bogeyed 17 and parred the par-5 18th. Kang birdied Nos.12, 13 and 14 to pull within a stroke, but bogeyed the 15th.

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"I'm not going to lie, it shook me up pretty bad," McDonald said.

"I had to gather myself and get my heart rate under control after I made bogey on 13 and Danielle went back to back on birdies on 13 and 14.

Bianca Pagdanganan of the Philippines was two strokes back in third place after a 70.

Mina Harigae (67) and Carlota Ciganda (69) were 13 under, a stroke ahead of Ariya Jutanugarn (69) and Kirk.