NEW HAVEN, Conn. (AP) _ Lindsay Davenport sure has Amelie Mauresmo's number, especially at the Pilot Pen tournament.

Davenport, the defending champion, knocked off the No. 1-ranked Mauresmo 6-4, 7-5 Thursday night to advance to the semifinals of the U.S. Open tuneup. Davenport has won their last nine meetings, dropping just one set over that stretch.

And in New Haven, the two have played each other five times since 1999, with Davenport going 5-0, including in last year's final.

Both players appeared a little rusty at times Thursday, evidence of long layoffs due to injuries. Davenport has missed most of the season with a bad back; this is her fifth tournament of 2006. Her service game was solid most of the night and that made the difference against the often-erratic Mauresmo.

Davenport closed out the first set with two straight aces. She had eight in the match and was able to mix up her delivery, hitting clean angles and painting the centre line.

Mauresmo _ seeded No. 1 at the U.S. Open, which starts Monday _ was in her first tournament since winning Wimbledon in early July. She often found herself flailing at a Davenport winner or scrambling to win a point on a jaw-dropping shot. Mauresmo struggled with her serve, losing nine straight points on it in the second set.

Davenport's next opponent is Samantha Stosur, who lost in qualifying but moved into the main draw when Shahar Peer withdrew with a foot injury. Stosur beat Marion Bartoli 7-6 (2), 6-0.

``I've been playing well the last few weeks _ wanted to keep that going this week,'' Stosur said. ``That's what I've managed to do. I've played a lot of matches, which is exactly what you want going into a Grand Slam.''

In other quarter-finals, Svetlana Kuznetsova took advantage of Elena Dementieva's nine double-faults to win 6-3, 3-6, 6-2 in a rematch of the 2004 U.S. Open final.

``Everybody knows that her serve is not the best thing in her game,'' said Kuznetsova, who won that Grand Slam championship. ``But still, she's improving the serve, and sometimes she can serve to the backhand. Still, she's not confident. You can see, she makes lots of double-faults.''

The match turned in the fourth game of the third set, when Dementieva had two double-faults and screamed in frustration after sending a forehand wide at break point. The third-seeded Dementieva double-faulted five times in the third set alone.

``It was very difficult to come back, because she was serving very well and she was keeping her serve,'' Dementieva said. ``I was fighting, I was staying there. But, you know, it was very difficult to come back when you just lost your chances in the beginning of the set. She didn't give me any chances afterwards.''

Her semifinal opponent will be second-seeded Justine Henin-Hardenne, who eliminated Mara Santangelo 6-2, 6-3. A knee injury had sidelined Henin-Hardenne since losing the Wimbledon final to Mauresmo. She entered New Haven with a wild card to prepare for the U.S. Open.

``I'm not a big fan of playing the week before a Grand Slam, but that's the way it is this year,'' Henin-Hardenne said. ``Mentally I'm fresh. That's a good thing for me.''

In the men's quarter-finals, Robin Soderling beat Jurgen Melzer 6-3, 6-2, and Agustin Calleri defeated Nicolas Massu 6-3, 3-6, 6-4.