Venus and Serena Williams [Images] served their way into the U.S. Open quarter-finals with impressive straight-sets victories Sunday, setting up a possible clash between the American sisters in the final four.

Venus never lost her serve during a 6-4 6-2 drubbing of Ana Ivanovic, while Serena stopped France's [Images] Marion Bartoli 6-3 6-4 by blasting 10 aces and landing 73 percent of her first serves.

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A Venus-Serena match-up would be their fourth at Flushing Meadows and the first since meeting in the 2005 fourth round.

"That would be awesome because it would mean that there is a Williams in the final and it would mean that Americans have a chance to win," said Venus, who won the 2005 encounter.

Standing in the way of Serena's possible clash with Venus is top seed and world number one Justine Henin [Images], who demolished 15th seed Dinara Safina 6-0 6-2 in just 59 minutes.

"We both have a lot of character and a lot of personality," Henin said of her quarter-final opponent.

"We both have been very strong mentally on the court the last few years.

"There's a lot of respect professionally between the two of us, that's for sure. 

On the men's side, second seed Rafael Nadal [Images] said he continued to suffer from nagging injuries to both knees but his ailments hardly apparent during a 7-6 6-2 6-1 victory over Frenchman Jo-Wilfried Tsonga.

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Nadal made only 14 unforced errors and never lost his serve against the 74th-ranked Tsonga.

"It was important for me to win in straight sets," the second-seeded Spaniard said. "For my knees it's better because I can be a little bit more relaxed for the next match."

In the fourth round, Nadal will face compatriot David Ferrer, who needed just under four hours to defeat Argentine David Nalbandian 6-3 3-6 4-6 7-6 7-5.

Third seeded Novak Djokovic of Serbia recovered from his four-hour, 44-minute victory over Radek Stepanek on Friday to ease past Argentine Juan Martin Del Potro 6-1 6-3 6-4.

"I was serving really well and he broke me only one time," said Djokovic, who hit 74 percent of his first serves. "I'm really happy the way I played."

Other third-round winners included Stanislas Wawrinka, Juan Ignacio Chela, Carlos Moya [Images] and Juan Monaco.

Eighth seed Tommy Robredo of Spain was eliminated, falling 6-1 6-3 6-2 to 88th-ranked, 19-year-old Ernests Gulbis of Latvia.

Venus Williams has not lost a set during her four matches and in the quarter-finals will face 2006 semi-finalist Jelena Jankovic, a 6-4 4-6 6-1 winner over 19th seed Sybille Bammer of Austria.

Third seed Jankovic was broken in the first game of the third set but swept the next six to set up a clash with Williams, who has lost her last three meetings with the Serb.

Ivanovic, the French Open finalist, was unable to keep up with the punishing serve or angled groundstrokes by Venus.

She said the 12th seeded American might be ready to claim her first Open crown since winning the second of two straight titles in 2001.

"She's the type of player that plays better each match, and as the tournament progresses she is raising her level," Ivanovic said.

"She is definitely playing some good tennis and has a good chance (to win)."

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