Beijing will witness the best lineup since tennis returned as a full medal sport in Seoul 1988 as world number ones Roger Federer and Ana Ivanovic head a strong field at the Olympic tennis tournament next month.

Fifty-six players in both men's and women's singles gained direct entry based on their singles rankings immediately after last month's French Open with 16 of the men's top 20 and 15 of the women's top 20 confirmed for the tournament which will run from Aug. 10-17.

Swiss Federer, who was beaten by Spaniard Rafael Nadal in finals of the French Open and the Wimbledon, is attempting to win his first Olympic medal after a surprise defeat in Athens four years ago by Czech Tomas Berdych.

"The Olympic medals are something that would make me very proud. To bring back a medal home to Switzerland would be very nice because we don't win that many, but I'm obviously gunning for the gold medal," said Federer, who had his first Olympic taste in Sydney where he finished fourth.

Federer will be joined by compatriot Stanislas Wawrinka, who now ranked 10th in the world.

World number two Nadal, on a surge after two Grand Slam wins this season and poised to take over the number one slot, is also eager for the Olympics to get underway.

"To play in the Olympics is very special, because when you're very young you always see the Olympic Games on television," said Nadal, who will be making his singles debut in Beijing having played doubles with Carlos Moya at Athens four years ago.

"You represent your country, that's the same as the Davis Cup, but at the same time it's completely different. When I play Davis Cup I always have this big motivation and I think in the Olympics I am going to have the same."

Spain boasts an all-star men's squad and claimed all four entries in singles' draw, featuring David Ferrer (5th), Nicolas Almagro (12th) and Tommy Robredo (14th) apart from Nadal.

Medal hopefuls will also include Russians and Argentines who both filled four slots in the men's draw. The Russians will be headed by world number four Nikolay Davydenko while the Argentine contingent is led by David Nalbandian.

In women's singles, Serbs, Russians and Americans are posed to be the best bets. World number one and newly-crowned French Open champion Ivanovic, defeated by China's Zheng Jie in the third round of the Wimbledon, will be making her Olympic debut. Her compatriot Jelena Jankovic, now ranked second in the world, also looks to the coveted title.

But the Serbian charge should be wary of the Russia's big names including Maria Sharapova (3rd), Svetlana Kuznetsova (4th), Elena Dementieva (6th) and Dinara Safina (9th).

The Williams sisters, who claimed the Olympic titles in both singles and doubles at Sydney 2000, rode on the Wimbledon triumph in July and will eye more at Beijing.

Olympic tennis has produced women's champions familiar even to casual fans. Gold medalists have included Jennifer Capriati as a 16-year-old in 1992, evergreen star Lindsay Davenport in 1996, Venus Williams in 2000, and Justine Henin in 2004. All are winners of multiple Grand Slam titles.

In contrast, men's top players seem to put the Wimbledon, Roland Garros and the Australian and US Opens as the benchmark of success.

Chile's Nicolas Massu and American Mardy Fish, the finalists in 2004, have never reached a major semifinal. Marc Rosset of Switzerland and Miloslav Mecir of Czechoslovakia were other surprise gold medalists.