West Australian Hannah Green saved her best to last, a birdie and an eagle on her back nine leaving her with a final-round 69 to finish tied for fourth at six-under.

She will collect $US117,507 ($A183,000) in prize money for her troubles.

Gabi Ruffels was Australia's next best. In an eventful round, the 23-year-old carded six birdies along with three bogeys and a double bogey to finish tied for 19th after she called a penalty on herself before the final round.

Minjee Lee (72) and Karis Davidson (73) were a shot further back at one-over for the week and a share of 22nd place.

Having gone into the final round with a three-stroke lead, Khang struggled for most of Sunday.

She made a four-foot birdie putt on the par-4 18th hole at Shaughnessy Golf and Country Club to force the play-off.

Ko hit her tee shot on the first play-off hole into the hazard left of the fairway and took a double bogey after a penalty shot.

“My game has been trending in the right direction lately and I think this just adds the self-confidence that, hey, I can win out here." - Meghan Khang.

The 25-year-old Khang placed her second shot to the fringe left of the pin on 18 and two-putted for her first win in eight years on the LPGA Tour, giving her caddie a giant hug after it dropped.

She shot two-over 74 in the final round to finish at nine-under 279.

“My game has been trending in the right direction lately and I think this just adds the self-confidence that, hey, I can win out here,” Khang said. “I have won out here now.”

Fellow U.S player Andrea Lee needed to finish at least 13th to earn one of the seven automatic qualifying spots for her nation's Solheim Cup team.

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She just missed a birdie on 18 to shoot 70 in the final round, leaving her 11th at two-under with several players still on the course.

After a nearly hour-long wait, Lee tied for 13th, earning a spot in the September 22-24 matches in Spain.

Lexi Thompson earned the eighth U.S Solheim Cup spot based on world rankings despite missing the cut by eight.