Defending champion Serena Williams beat Kaia Kanepi of Estonia 6-3, 6-3 on Monday to set up a repeat of last year's Sony Ericsson Open final against world number one Justine Henin in the last eight.

Henin, seeking her first title of 2008, wasted little energy in a 6-2, 6-2 fourth-round win over world number 53 Elena Vesnina of Russia.

Williams's sister Venus lined up a quarterfinal against world number four Svetlana Kuznetsova after beating Danish teenager Caroline Wozniacki 6-3, 6-3.

Third-seeded Kuznetsova sealed a 7-6, 6-3 victory over 16th-seeded Shahar Peer of Israel, avenging her defeat by the same player in Miami last year.

Men's world number one Roger Federer had a short day at the office when his opponent Robin Soderling of Sweden retired from their third-round match trailing 6-4, 3-0 because of illness.

Federer served well but did allow world number 39 Soderling to break him in the fifth game of the first set. "It's a big difference between not playing at all or playing one and a half sets," Federer said."

Roddick survives

Meanwhile, Andy Roddick was tested by qualifier Ivo Minar of the Czech Republic before winning 7-6, 6-4.

Roddick won the first set on his second set point in the tiebreak when world number 86 Minar's backhand hit the top of the net and landed wide.

Roddick was up a service break in the second set, but allowed Minar to level in the eighth game.

Serena Williams looked in much better form against world number 61 Kanepi after she made 60 unforced errors against Flavia Penetta in the third round.

"I definitely had a lot less unforced errors, so I think that was pretty key," Williams said. "It was kind of up and down, though. She didn't give me any kind of rhythm."  One day after upsetting world number two Ana Ivanovic, experienced American Lindsay Davenport struggled with the wind in a 6-3, 6-4 loss to 13th-seeded Dinara Safina.
"This is the first match that I just really felt like I couldn't figure out a way to kind of get back into it," said Davenport, who has won four titles since returning to the tour after giving birth to her first child last June.

Paes-Hesh to clash

Leander Paes and Mahesh Bhupathi set up a quarter-final clash against each other in the doubles, after winning their second round doubles matches here.

Seeded fourth Bhupathi and Mark Knowles of Bahamas came from behind to beat Russian Igor Andreev and Xavier Malisse of Belgium 2-6, 6-2, 10-5.

Paes, and his Australian partner Paul Hanley, seeded eighth, booked the last eight berth after pipping German-Dutch combine of Kas Christopher and Rogier Wassen 6-4, 4-6, 10-7 in the second round.