Teenager Coco Gauff is the biggest name on the U.S. Olympic Tennis Team roster for Tokyo, one lacking many of the country's top players. 

The top two American women, Sofia Kenin and Serena Williams, as well as the top three men -- John Isner, Reilly Opelka and Taylor Fritz -- opted not to play. Madison Keys, who could have been pulled onto the roster in Kenin and Williams' absence, also declined, as did Sebastian Korda, Sam Querrey and Steve Johnson for the men.

Jennifer Brady, Jessica Pegula and Alison Riske are joining the 17-year-old Gauff on the women's singles roster. Nicole Melichar and Rio mixed doubles gold medalist Bethanie Mattek-Sands are the doubles picks. 

The scheduled women's doubles teams are Gauff with Melichar and Mattek-Sands with Pegula.

Tokyo will be the first Olympics without one of the Williams sisters since 1996. While Venus Williams -- the most decorated tennis player in Olympic history -- did not qualify in singles, she could have been chosen in doubles, in which she's won three Olympic gold medals. It's not clear if she was not chosen, or if she declined an invite like Serena. 

Tommy Paul, Frances Tiafoe, Tennys Sandgren and Marcos Giron comprise the men's singles roster (Paul is the only one who qualified outright). Rajeev Ram, who won mixed doubles silver in Rio, and Austin Krajicek are the doubles picks. 

The scheduled men's doubles team are Ram with Tiafoe and Krajicek with Sandgren. The American mixed doubles team or teams will be announced at a later date.

All of the U.S. singles players are first-time Olympians. While the roster was ravaged by opt-outs, the U.S. is certainly not the only nation that will be without its stars in in Tokyo. So far, Spain's Rafael Nadal, Austria's Dominic Thiem and Romania's Simona Halep also aren't going, and Switzerland's Roger Federer said he will make his decision after Wimbledon. 

Star players confirmed for the Tokyo Games include Naomi Osaka, who represents the host nation, and Novak Djokovic

The tennis competition begins July 24 in Tokyo.