American sisters Serena and Venus Williams [Images] powered on towards a likely gold medal showdown with easy second-round wins in the Olympic [Images] singles on Tuesday.

Serena needed just 44 minutes to blow away Australian Samantha Stosur 6-2, 6-0 on day three of the tennis tournament.

Shortly afterwards on Centre Court Wimbledon [Images] champion Venus was not quite as ruthless but still had far too much for Czech Iveta Benesova, winning 6-1, 6-4.

"It was clean," fourth seed Serena, who next faces France's [Images] Alize Cornet, told reporters. "I played really clean matches in the past and the next one would be kind of streaky. I don't want to do that any more."

Serena and Venus, winners of 15 grand slam singles titles between them, are in opposite sides of the draw and with seeds tumbling they look destined to meet in the final.

After Russian third seed Svetlana Kuznetsova's [Images] defeat by China's Li Na on Monday, two more women's seeds fell.

Slovak Daniela Hantuchova [Images], seeded 10, fell to Denmark's Caroline Wozniacki 6-1, 6-3 while Pole Agnieszka Radwanska, the eighth seed, lost a tense battle against Italian Francesca Schiavone 6-3, 7-6.

China now have just two players left in the women's singles after Peng Shuai's 6-2, 6-2 defeat by 15th seed Cornet. Li and Zheng Jie play later.

American doubles duo Bob and Mike Bryan launched their Olympic bid with a 6-2, 6-1 defeat of Bahamian team of Mark Knowles and Devin Mullings.

In the men's section, Spain's Rafael Nadal [Images] thrashed Australian Lleyton Hewitt [Images] 6-1, 6-2 in the day's highlight clash and top seed Roger Federer [Images] steamrolled El Salvador's Rafael Arevalo, ranked 447th in the world, 6-2, 6-4.

While Nadal faced a familiar foe, Federer had probably never heard of Arevalo who arrived on Centre Court with a ranking of 447.

Nadal had never beaten Hewitt on hardcourts and trailed the Australian 4-3 in career meetings.

Statistics counted for nothing, however, as Nadal sent Hewitt scuttling to all corners of the court a display of spin, power and deadly precision.

"I felt like he played flawless tennis out there tonight," Hewitt told reporters

However, Chilean Nicolas Massu's hopes of emulating his incredible run to the singles title in Athens four years died at the hands of Argentine David Nalbandian, who won 7-6, 6-1.

And Nikolay Davydenko became the highest-ranked men's casualty so far when he fell to 7-5, 6-3 to Paul-Henri Mathieu, one of three Frenchman into the third round.

But Novak Djokovic [Images] of Serbia made no mistake when he saw off Germany's [Images] Rainer Schuettler 6-4, 6-2.