Serena Williams kept her Australian Open title defence on track by breezing into the fourth round with a 6-0, 6-3 victory over Carla Suarez-Navarro in Melbourne on Saturday.

The 11-time Grand Slam champion had too much power and variety for her Spanish opponent, winning in 80 minutes to set up a last-16 meeting with Sam Stosur, a 6-4, 6-1 winner over Italy's Alberta Brianti.

"I think she's playing great. She beat me the last time we played, so she has a lot of momentum. A ton of momentum," Williams said.

"I definitely expect the crowd to root for Sam. Hopefully, my mom will cheer for me. I should be fine."

Meanwhile, sixth seed Venus Williams beat Casey Dellacqua 6-1, 7- 6 (4), and seventh seed Victoria Azarenka continued her impressive run of form by outclassing Tathiana Garbin 6-0, 6-2. The Belarusian has now lost only eight games all tournament.

"I think I did very well today. I had a good game plan and followed it perfectly," said Azarenka. "I was going for my shots and playing comfortably and confidently."

Azarenka next plays No. 9 seed Vera Zvonareva, who downed Gisela Dulko 6-1, 7-5.

Next up for Venus is Francesca Schiavone after the 17th seed pulled off a 6-2, 6-2 victory over 10th seed Agnieszka Radwanska.

Also progressing through is China's No. 16 seed Li Na, who beat Daniela Hantuchova 7-5, 3-6, 6-2. Li next faces the winner between Caroline Wozniacki and Shahar Peer.

In men's draw, 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 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."

The 15-time Grand Slam champion, contesting his 11th successive Australian Open, will face home favorite Lleyton Hewitt on Monday after 2006 finalist Marcos Baghdatis was forced to retire when trailing 6-0, 4-2.

Nikolay Davydenko, Federer's potential quarterfinal opponent, extended his impressive winning run with a 6-0, 6-3, 6-4 victory over No. 30 Juan Monaco of Argentina.

Davydenko will next face Fernando Verdasco, who advanced when Austria's Stefan Koubek retired due to a virus after losing the first set 6-1.

Frenchman Jo-Wilfried Tsonga, a finalisht here in 2008, plundered his way into the last 16 with a thrilling 6-4, 3-6, 6-1, 7-5 victory over Germany's Tommy Haas.