Serena and Venus Williams to play Olympic doubles

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 while taking the gold together in 2000 and 2008.

Venus Williams also won the 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.

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.

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.