Mary Pierce breezed into the US Open semi-finals with a 6-4 6-1 defeat of fellow Frenchwoman Amelie Mauresmo.
The 2005 French Open finalist broke third seed Mauresmo twice in each set with some stinging groundstrokes.
It was the first time Pierce, who upset seventh seed Justine Henin-Hardenne in the previous round, had got the better of Mauresmo in six years.
Pierce will now meet Russian sixth seed Elena Dementieva for a place in the final at Flushing Meadows.
Powerful rallies dominated the opening exchanging between the two Fed Cup team-mates in New York.
Pierce's pressing play on Arthur Ashe Cout told as she forced Mauresmo into mistakes to secure a break at 4-2.
The third seed responded with some clever passing shots and good skill at the net to get the set back on serve.
But Mauresmo's relief was short-lived as she followed a double-fault with a forehand which looped long to hand Pierce the set.
While Mauresmo crumbled, Pierce stayed composed to break at 2-0 and then again to move within one game of the match.
The 30-year-old closed out the encounter in just over an hour to reach the last four of the US Open for the first time.
"What can I say?" said the 12th seed.
"I am 30 and I have been on the tour for 17 years and there are still firsts for me. That's pretty amazing.
"I am just feeling so great. I am healthy and able to play out here in front of my fans.
"Everything that's happened in my life - I'm just so grateful."
Mauresmo, a close friend of Pierce off court, admitted she was playing at a different level.
"There's no comparison," Mauresmo said. "She just played a better match than me today.
"She has the confidence now, which is huge. She goes for every shot."