Defending champion Kim Clijsters increased her U.S. Open winning streak to 19 matches by beating Sam Stosur 6-4, 5-7, 6-3 in the quarterfinals Tuesday.
The No. 2-seeded Clijsters will face No. 3 Venus Williams in the semifinals, a matchup between two women who both have won two titles at Flushing Meadows.
Clijsters and the fifth-seeded Stosur, the runner-up at this year's French Open, had trouble serving in windy conditions.
There were a total of 18 service breaks, including a stretch in which there were nine in 10 games.
But Clijsters managed to hold in each of her last two service games.
Stanislas Wawrinka beat Sam Querrey in five sets to put two Swiss men in a major quarterfinal for the first time in the Open era - and keep the Americans out of that round in the U.S. Open for the second straight year.
After waiting out that nearly 4 1/2 -hour match, Williams defeated French Open champion Francesca Schiavone 7-6 (5), 6-4.
Wawrinka won 7-6 (9), 6-7 (5), 7-5, 4-6, 6-4 to join a countryman whose presence this deep in a major tournament is just assumed: Roger Federer.
Wawrinka will next face Mikhail Youzhny, who beat Tommy Robredo, 7-5, 6-2, 4-6, 6-4. Also, Fernando Verdasco rallied from two sets down for a 5-7, 6-7 (8), 6-3, 6-3, 7-6 (4) victory over fellow Spaniard David Ferrer to reach the quarterfinals.