MIAMI, March 30: Defending champion Andre Agassi wasted little time in dispatching Max Mirnyi of Belarus at the Nasdaq-100 Open on Monday, wrapping up a 6-2 6-2 third round victory in just 52 minutes.

The fourth-seeded American moves on to a showdown against Agustin Calleri for a place in the quarterfinals after the Argentine advanced with a 6-4 7-6 victory over Australian wildcard Todd Reid.

The home crowd were treated to another American victory when Andy Roddick overcame a determined challenge from Jonas Bjorkman to beat the Swede 6-4 3-6 6-3. The match was also a dress rehearsal for a Davis Cup quarterfinal tie in just over a week when Roddick is likely to face Bjorkman again as the U.S. take on Sweden at Delray Beach.

"Obviously you can't help but think forward but winning tonight really doesn't do anything to help our chances in the Davis Cup," Roddick said. The second seeded Roddick awaits the winner of the match between Argentina's Guillermo Canas and Belgium's Xavier Malisse.

In the women's event, top seed Serena Williams was also in a hurry, easing past Russian teenager Maria Sharapova 6-4 6-3 to earn a place in the quarterfinals.

Playing only her third match since returning from an eight-month lay-off, Williams defeated the 16-year-old in an hour and 15 minutes. Having been delayed for more than two hours by light rain, Williams looked anxious to see off Sharapova quickly, hitting 26 winners to the Russian's two.

Williams, who beat Marta Marrero and Elena Likhovtseva in previous rounds, now plays Jill Craybas after the unseeded American overcame ninth seed Paola Suarez 4-6 6-4 7-6.

The Nasdaq-100 Open is Williams's first tournament since she won Wimbledon last July. She underwent knee surgery in August 2003 and missed the U.S. and Australian Opens.

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