MELBOURNE, Australia — Serena Williams moved a step closer to successfully defending her Australian Open title and extracted some family revenge today with a 6-0, 6-3 victory over Carla Suarez Navarro.

Last year, Suarez Navarro beat Venus Williams in the second round and made it to the quarterfinals.

The Spaniard didn't even get close this time, and the Williams sisters remained on course for a semifinal meeting when Venus beat Australia's Casey Dellacqua, 6-1, 7-6 (4), closing with an ace on her third match point.

Serena Williams' only real difficulty was in closing the first set, needing eight set points in a game that went to deuce 13 times and lasted longer than the previous five games combined.

"It was definitely the toughest 6-love set," she said. "I thought, 'OK, Serena, don't put too much pressure on this. Worst case scenario it will be 5-1.' But way to keep fighting."

Top-ranked Roger Federer had no trouble in a 6-3,6-4, 6-4 win over No. 31 Albert Montanes of Spain. It was the 28-year-old Swiss star's 50th win at Melbourne, where he has collected three of his record 15 Grand Slam singles titles.

"It was important to come through the first week," Federer said. "I feel good, I feel confident. Physically I'm fine and mentally fresh and that's the way you want to go into the second week."

Nikolay Davydenko, Federer's potential quarterfinal opponent, rolled to a 6-0,6-3, 6-4 victory over No. 30 Juan Monaco of Argentina.

Novak Djokovic, who beat Federer in the semifinals en route to the 2008 title, had a 6-1, 6-1, 6-2 win over Denis Istomin of Uzbekistan. The 22-year-old Serb will play Poland's Lukasz Kubot, who had a walkover when No. 20 Mikhail Youzhny withdrew from their scheduled third-round match due to right wrist pain.

Belgian Kim Clijsters came to the Australian Open as an inspiration to her countrywomen and mothers everywhere after her unexpected U.S. Open victory.

Any chance of back-to-back major titles ended in 52 minutes Friday evening in a 6-0, 6-1 third-round loss to 19th-seeded Nadia Petrova."I was completely off," Clijsters said. "I think tennis-wise, I didn't feel the ball at all."