Kim Clijsters scrapped her way into the US Open semi-finals with a tough 4-6 7-5 6-1 win over Venus Williams.
Williams proved too strong for the fourth seed in a mundane opener and broke twice to take a one-set lead.
Sloppy play saw seven breaks of serve in the second but the match sparked into life when Clijsters earned the decisive break at 6-5 to level.
The Belgian fourth seed steamrolled through the third set to set up a semi-final with Maria Sharapova.
In cooling conditions at Flushing Meadows, Williams started strongly to break Clijsters at the first time of asking.
But the Wimbledon champion faltered and Clijsters broke back with a combination of athletic play and clever backhands.
Williams immediately recovered and her powerful pressure forced Clijsters into surrendering a second break which cost her the set.
A series of unforced errors by Clijsters gifted the tenth seed an early break in the second as she whacked the ball long.
Clijsters dug deep to break back at 3-2 but the 22-year-old could not consolidate on her own serve and handed the American another easy break.
In a rapid turn around, a combination of Williams' errors and renewed grit from Clijsters saw her break twice.
It was no surprise when the risky tennis saw both exchange breaks yet again but this time it was Clijsters who sealed the set to take the match into a decider.
The fourth seed carried the momentum forward and confidently broke Williams twice to take a 4-1 lead.
The Belgian, who came to Flushing Meadows as the in-form hardcourt player, broke the former champion again to complete an amazing comeback.
"I just tried to keep fighting and keep running for each ball." said a delighted Clijsters who missed most of the 2004 season because of wrist injuries.
"After my surgery I enjoy every win much more but this definitely means more than any win before my surgery."
Clijsters has won all three of her previous matches against Sharapova, but said: "She is a tough player and a very talented girl."