Martina Navratilova admitted the chance to compete at the Olympics in Athens was a "a carrot I couldn't resist".
The 47-year-old will play doubles with United States team-mate Lisa Raymond, who was called up for the injured Jennifer Capriati.
"It's all a new experience, and this will be my only one," she said.
"It's great to be wearing the uniforms and it's just nice to be part of a team. You really feel like you're pulling for each other."
Twenty-seven of the world's top 30 will compete in the men's singles competition, and 23 of the top 30 women will also be taking part.
Tim Henman is Britain's only entrant, while the USA's formidable line-up also includes Andy Roddick, Taylor Dent, Jennifer Capriati and the Williams sisters.
Spain also have a strong entry in the men's singles - Carlos Moya, Juan Carlos Fererro, Tommy Robredo and Feliciano Lopez - while Switzerland has only one - Roger Federer.
Fifty-three countries will be represented at the tennis
event in Athens, one more than competed in Sydney.
It is the fifth Games since tennis returned as a full medal sport in 1988.
"This is the best field we have had for tennis in the Olympic Games," said International Tennis Federation president Francesco Ricci Bitti.
"It took a few years for the players and the fans to understand what an honour and a privilege it is to compete for your country at the Olympic Games.
"But the response that we have received shows that the Olympics is now one of the
most important events in tennis."
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It took a few years for the players and the fans to understand what an honour and a privilege it is to compete for your country at the Olympic Games
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