World number one Amelie Mauresmo and number two Justine Henin-Hardenne came through their first matches since the Wimbledon final to reach the New Haven quarter-finals on Wednesday.
Wimbledon champion Mauresmo overcame Russian qualifier Galina Voskoboeva 4-6, 6-1, 6-2 and Henin-Hardenne had to work harder than the scoreline suggests for her 6-4, 6-2 win over Anabel Medina Garrigues of Spain.
Having delayed her return to the Tour because of a shoulder injury, top seed Mauresmo shrugged off a slow start to set up a clash with former world number one Lindsay Davenport.
Frenchwoman Mauresmo was lethargic in the early stages and Voskoboeva, the world number 93, took advantage in the first set.
Any thoughts of an upset were soon dashed, however, as Mauresmo cruised through the next two sets.
"I was not surprised it took me some time to get into the rhythm," Mauresmo said.
"I think it's a little normal. There were a few good things and a few things still need working on but, hopefully, they will get there by next week (before the U.S. Open)."
Defending champion Davenport set up a repeat of last year's final with a confident 6-4, 6-2 victory over Italian Francesca Schiavone.
The American, in just her second tournament back after five months out with a back problem, eased through in 68 minutes.
Davenport has won 11 of her 14 meetings with Mauresmo, including the past 10, but said their quarter-final would be a different match.
"It will be interesting to play her a year later to see the improvement she has made," Davenport said.
"She's kind of a different player with a couple of grand slams under her belt. It should just be fun to see how both of us are right now."
Belgian Henin-Hardenne, the French Open champion, was pushed hard by Medina Garrigues before advancing to the last eight.
MAMMOTH GAME
A mammoth fourth game of the second set proved to be crucial as the second seed held for 2-2 before reeling off the next four games to clinch victory.
"I knew it would be a tough match after six weeks out," Henin-Hardenne said.
"I really had to fight hard but now I have won I can say that it was a good match for me because it was the kind of match that I was able to find my rhythm."
She will play lucky loser Mara Santangelo in the quarter-finals after the Italian advanced when Li Na of China pulled out through injury before their match.
Third seed Elena Dementieva survived a second-set wobble to defeat Slovakia's Daniela Hantuchova 6-2, 5-7, 6-0.
The Russian, who won the Los Angeles title this month, now plays compatriot Svetlana Kuznetsova in a repeat of the 2004 U.S. Open final, which Kuznetsova won.
Fourth seed Nadia Petrova was upset 4-6, 6-4, 7-6 by Marion Bartoli of France.
In the men's event, second seed Nikolay Davydenko took his place in the last eight with a 6-4, 6-1 win over Paradorn Srichaphan of Thailand
But third seed Marcos Baghdatis was ousted 6-3, 6-7, 7-5 by unseeded Swede Robin Soderling and number five David Ferrer was crushed 6-3, 6-1 by number 10 seed Agustin Calleri of Argentina.
Belgian Olivier Rochus, Argentine Juan Ignacio Chela, lucky loser Juergen Melzer of Austria and Belgian Xavier Malisse all advanced to the last eight.
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