Russia's Svetlana Kuznetsova edged out compatriot Nadia Petrova 7-6 6-3 to move into the semi-finals where she will meet Lindsay Davenport.
Kuznetsova recovered from going 2-0 down in the opening set to rally and win a tight tie-break 7-4.
The ninth seed then stepped up a gear in the second set, breaking early on to win the set 6-3 to send Petrova out.
The 19-year-old Kuznetsova will be making her first-ever appearance in a Grand Slam semi-final.
Kuznetsova made a tentative start on Court 11 but was spurred into action after losing the first two games, breaking straight back.
The Russian sealed the first set and then raised her game to wrap up the match in one hour, 27 minutes.
Petrova, who had upset top seed Justine Henin-Hardenne, threatened to break back in the ninth game but Kuznetsova fended off her challenge.
"It will be great to play Lindsay on a big court here," said the 19-year-old.
"Of course all the crowd will be with her and she is in the form of her life.
"But I will go and play my game and enjoy it."
Kuznetsova's semi-final spot at Flushing Meadows goes some way to making amends for her performances in Grand Slams this season.
The Russian squandered a match point in the French Open to eventual winner Myskina in the fourth round and then crashed out of Wimbledon at the first stage.
"This has been a strange year for me," admitted Kuznetsova.
"It's been good but could have been so much better."