Brazilians Juliana Silva and Larissa Franca remained unbeaten in the Olympic beach volleyball tournament, winning their first knockout stage match Friday.
Silva and Franca, who made it through pool play without dropping a set, rolled 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, the United States' No. 2 team of April Ross and Jennifer Kessy will play Simone Kuhn and Nadine Zumkehr of Switzerland and Austrian sisters Stefanie and Doris Schwaiger take on Russians Anastasia Vasina and Anna Vozakova.
Defending Olympic champions Todd Rogers and Philip Dalhausser of the U.S. will also be in action Friday night against Italy's Paolo Nicolai and Daniele Lupo to begin the men's knockout stage.
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.
Spain's Pablo Herrera Allepuz and Collado Gavira play Brazil's Ricardo Santos and Pedro Cunha later.