Venus Williams of the United States returns a volley to Ana Ivanovic of Serbia at the U.S. Open tennis tournament in New York yesterday. Williams won 6-4, 6-2. - AP

NEW YORK (Reuters):

Venus Williams underlined her title credentials at the U.S. Open yesterday after she reached the quarter-finals with an impressive 6-4, 6-2 victory over fifth seed Ana Ivanovic.

The Wimbledon champion, seeded 12, was close to her dominant best as she made it four wins out of four against the Serb, clinching victory in 80 minutes.

"I have a lot of respect for her as a player so I knew I had to play well because she is very good," Williams told the crowd. "I just got the important points today."

Her sister, twice former champion Serena, also advanced to the quarter-finals yesterday with a 6-3, 6-4 victory over Marion Bartoli, raising her game in time for another possible championship run.

The eighth-seeded Serena had 10 aces, landed 73 per cent of her first serves and blasted 32 winners against the Wimbledon finalist to play her best match of the tournament.

Got better with each match

"Each match I feel like I've gotten better," said the younger Williams sibling. "I'm still not near where I want to be. But I feel like I'm doing better, which is important."

On the men's side, second seed Spaniard Rafael Nadal showed no lingering effects from a nagging knee injury with a 7-6, 6-2, 6-1 victory over Frenchman Jo-Wilfried Tsonga.

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

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.

In a mild upset, Argentine Juan Ignacio Chela tamed Croatian 12th seed Ivan Ljubicic 6-4, 6-7, 2-6, 6-3, 6-3 in three hours, 44-minutes.

The hard-hitting Ljubicic had 80 winners and 64 unforced errors but was unable to close out the steadier Chela, the 20th seed who had just seven errors in the final two sets.

World number one Justine Henin was slated to face 15th seed Dinara Safina later yesterday. If Henin beats Safina, she will face Serena in a highly anticipated quarter-final match-up.

Henin, the 2003 Open champion, had knocked Serena out in both the French Open and Wimbledon quarters this year.

"I'm going in feeling like I don't have anything to lose," said Serena. "I'm excited about the prospect of meeting her again. She's playing well and fighting for everything. She believes that she can win."