WIMBLEDON, England (AP) -- Serena and Venus Williams have been chosen to extend their unbeaten streak in Olympic doubles when they seek a third gold medal in the event beginning late next month.
Andy Roddick and John Isner were selected for men's doubles on the U.S. team announced Tuesday.
As expected, the Olympic eligibility of the Williams sisters received final approval from the International Tennis Federation, and they'll play singles as well as doubles. They've never lost in Olympic doubles competition, taking the gold together in 2000 and 2008.
Venus Williams also won gold in singles in 2000, and she's the only three-time gold medalist in U.S. tennis history. Next month she'll become the first American tennis player to compete in four Olympics.
Williams lost in the first round Monday at Wimbledon, which will also be the site of the Olympic tournament beginning July 28. She expects to play both singles and doubles in the Games even though she has been slowed in recent months by an autoimmune disease that causes fatigue.
The International Tennis Federation hailed the Olympic field as the strongest ever. It includes 19 of the current top 20 players in the men's and women's rankings, the exceptions being American Mardy Fish and Marion Bartoli of France, who declined to participate.
Direct acceptances were based on the singles rankings of June 11. Forty-five countries will compete.
As expected, the U.S. roster includes first-time Olympians Ryan Harrison, Donald Young, Isner, Christina McHale and Varvara Lepchenko, an Uzbekistan native who became a U.S. citizen in September.
Bob Bryan and Mike Bryan, who won the bronze in 2008, will again compete in doubles, as will the top-ranked women's doubles team of Liezel Huber and Lisa Raymond.
Two U.S. teams in mixed doubles will be chosen once players are on site. That event returns to the Olympics after an 88-year absence.