The world's best tennis players secured respective opponents in the upcoming Beijing Olympics as the draw was revealed on Thursday.

Current world number ones Roger Federer and Ana Ivanovic will play Russian 35th-ranked Dmitry Tursunov and Mariya Koryttseva of Ukraine, while second seeds Rafael Nadal and Jelena Jankovic, both soon to become the new world number ones, will play Italian Potito Starace and Cara Black of Zimbabwe.

Federer, going through the worse season since he became the world number one in 2004, will find many of his nemeses in his quarter featuring Frenchman Gilles Simon and Croat Ivo Karlovic, both winning over the Swiss in ATP Masters events held in North America last month.

If all goes well, the big-serving Karlovic will meet Federer in the third round, a rematch of the Cincinnati Masters weeks ago when the Croat claimed the first career win over Federer after a six-match losing streak. But he has to first defeat Czech Tomas Berdych in the opening round and the winner of Spaniard Tommy Robredo and Andreas Seppi from Italy in the second.

The top half of men's singles draw also features Russia's fourth seed Nikolay Davydenko, who will face 38-ranked Ernests Gulbis from Latvia. The Russian master heads towards a would-be quarterfinal clash agaisnt Spanish fifth seed David Ferrer, who will take on a hard first round match against Serb Janko Tipsarevic.

After claiming his fourth consecutive French Open trophy, Nadal beat Federer again at Wimbledon in a five-set epic on the Swiss maestro's Centre Court fortress. What's more, the bull-like youngster seems to improve on hard court too, winning the Masters event in Toronto and reaching the semifinals in Cincinnati last month.

"I came here to represent my country and I will do my best to claim a medal for Spain," said Nadal in a press conference on Wednesday night, having played the men's doubles event with Carlos Moya in Athens four years ago.

He might in the second round face Australian Lleyton Hewitt, who kept a 4-3 record in career and if all goes to plan, the upsurging Scot Andy Murray, who has just claimed the first career Masters title in Cincinnati, will be waiting for him in the quarterfinals.