Rafael Nadal of Spain returns a shot during his first round match of men's singles against Kei Nishikori of Japan in the 2010 Wimbledon Championships in London, Britain, June 22, 2010. Nadal won 3-0. [Xinhua/Zeng Yi]

World No. 1 men's singles Rafael Nadal and his counterpart in the women's singles Serena Williams both won their opening matches easily at the Wimbledon Championships on Tuesday.

The Spanish talent Nadal came back the grass-court Grand Slam tournament after missing the chance to defend his title last year due to a knee injury.

The 24-year-old knocked out his 20-year-old rival 6-2, 6-4, 6-4, setting up a challenge with Robin Haase from the Netherlands in the second round.

Nadal, collecting his fifth French Open title one month ago, didn't think he would need too much time to fully adjust from the clay court to the grass court.

"I think I'm okay," said the second seed. "First matches are very difficult. Always important to pass. After that, I can start to play much better."

Williams began her title defending journey with a much easier victory as the American saw off her first round opponent Michelle Larcher De Brito from Portugal 6-0, 6-4 after 63 minutes.

Her next rival is Russian Anna Chakvetadze who defeated Andrea Petkovic from Germany 3-6, 6-4, 6-4.

Meanwhile, the French Open runnerup Samantha Stosur, who knocked out Williams in the quarterfinals at Roland Garros, failed to pass the opening round after losing to Kaia Kanepi from Estonia 6-4, 6-4.

Serena Williams of the United States returns a shot during her first round women's singles match against Michelle Larcher De Brito of Portugal in the 2010 Wimbledon Championships, in London, Britain, June 22, 2010. Williams won 2-0. [Xinhua/Zeng Yi]

The French Open champion Francesca Schiavone of Italy has suffered first round exit on Monday.

Besides, the fourth seed Andy Murray and the sixth seed Robing Soderling both won the men's singles first round in straight sets. But Nadal's compatriots Fernando Verdasco, Nicolas Almagro and Juan Carlos Ferrero all failed in the first round.