Lunke struggled home in 75 but has a new chance on Monday

The Swede needed a birdie on the par-five last to steal victory at Pumpkin Ridge, Oregon.

But she could only manage a bogey to leave Kelly Robbins, Hilary Lunke and Angela Stanford tied for first place on 283 after four rounds.

The three Americans will now play off over 18 holes on Monday for the Major title.

FINAL LEADERBOARD (US unless stated) 283: Kelly Robbins, Hilary Lunke, Angela Stanford 284: Annika Sorenstram (Swe) 285: Aree Song (Kor) 286: Jeong Jang (Kor), Mhairi McKay (Scot)

Robbins set the clubhouse target after shooting a two-under-par closing round of 69.

And Stanford holed a monster birdie putt at the last to join her with a 74, before overnight leader Lunke struggled home with a 75 to complete the trio.

South Korean amateur Aree Song, 17, finished in fifth place on 285 after birdieing the last for a 74.

But Mhairi McKay's bid for glory ended in disappointment when she carded a second-straight round of 75.

"It wasn't quite the weekend I dreamt about on Friday," the Scot said.

"But I'm still thrilled with my championship. I've been working very hard on making a few changes to my swing and this makes it worthwhile.

"All in all, it was a really encouraging week."