Americans Todd Rogers and Phil Dalhausser, the defending men's Olympic beach volleyball champions, were knocked out of the London Games on Friday.
Rogers and Dalhausser lost to Italy's Paolo Nicolai and Daniele Lupo 21-17, 21-19 in 40 minutes at the Horse Guards Parade.
Rogers wasn't happy drawing the Italian team so soon in the knockout stage.
"They have beaten every team in the world," he said. "They could easily win a medal, I think."
The United States' No. 2 women's team of April Ross and Jennifer Kessy won their first knockout stage match 21-15, 21-19 against Simone Kuhn and Nadine Zumkehr of Switzerland.
Meanwhile, Brazilians Juliana Silva and Larissa Franca remained unbeaten in the Olympic beach volleyball tournament, rolling to a 21-10, 21-17 win over Madelein Meppelink and Sophie van Gestel of the Netherlands.
They will play Germany's Laura Ludwig and Sara Goller in the quarterfinals. Ludwig and Goller knocked off fellow Germans Katrin Holtwick and Ilka Semmler 21-16, 21-15 on Friday.
Later, Austrian sisters Stefanie and Doris Schwaiger beat Russians Anastasia Vasina and Anna Vozakova 21-17, 16-21, 15-9.
Also on the men's side, Poland's Mariusz Prudel and Grzegorz Fijalek beat Switzerland's Sascha Heyer and Seba Chevallier 21-18, 21-17; and Latvia's Martins Plavins and Janis Smedins topped Martin Spinnangr and Tarjel Viken Skarlund of Norway 21-18, 21-16.
Brazil's Ricardo Santos and Pedro Cunha beat Spain's Pablo Herrera Allepuz and Collado Gavira 21-18, 21-19.