Williams sisters, Henin reach Miami quarters

By Sandra Harwitt

MIAMI, Florida (Reuters) - 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 quarter-final 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 told reporters. "My opponent was a dangerous player. I think it was good for me to go out there and play today."

The newly engaged Andy Roddick, with his fiance Brooklyn Decker sitting beside musician Boyd Tinsley of The Dave Matthews Band in the stands, was tested by qualifier Ivo Minar of the Czech Republic before winning 7-6 6-4.