Seven members of the United States tennis team participated in the first round of matches in the men’s and women’s tournaments at the Rio Olympics, and five saw their runs come to an immediate end. Among those who lost was Venus Williams, with Belgium’s Kirsten Flipkens beating her in three sets 4-6, 6-3, 7-6 (5). Next up for Flipkens is Lucie Safarova of the Czech Republic, who advanced with a win over Italy’s Karin Knapp.

As for Keys, she had little trouble with Danka Kovinic of Montenegro. Seeded seventh in the women’s singles draw, Keys won in straight sets 6-3, 6-3 and converted three of her nine break point opportunities. Next up for Keys is France’s Kristina Mladenovic, who beat Serbia’s Aleksandra Krunic in straight sets.

Also losing in the women’s singles draw for the United States was Sloane Stephens, who tell to Canada’s Eugenie Bouchard in straight sets, 6-3, 6-3. Stephens had three double faults in the match, and Bouchard managed to break her serve three times. Yet to compete for the United States in the women’s draw is top seed and pre-tournament favorite Serena Williams, who takes on Daria Gavrilova of Australia Sunday morning.

Stephens joins three American men on the sidelines, including Jack Sock, who lost in straight sets to Japan’s Daniel Taro 6-4, 6-4. Sock had issues with his serve Saturday, finishing the match with five double faults and he won less than 50 percent of the points available on his second serve. By comparison Taro had just one double fault and he won 57 percent of the points on his second serve. Brian Baker fell in three sets to Japan’s Yuichi Sugita, 7-5, 5-7, 6-4. and Denis Kudla was defeated in straight sets by Slovakia’s Andrej Martin, 6-0, 6-3.

The one American male who managed to advance Saturday was 12-seed Steve Johnson, who beat Darian King of Barbados in straight sets, 6-3, 6-2. Next for Johnson is Gastao Elias of Portugal, with that match scheduled for Tuesday.