Duo Adriana Behar and Shelda Bede won the battle of Brazil to reach the last four of the Olympic women's beach volleyball competition.
The number two seeds defeated compatriots Ana Paula Connelly and Sandra Pires 15-21 21-13 15-13.
Americans Holly McPeak and Elaine Youngs have also reached the next stage after they beat Germany's Okka Rau and Stephanie Pohl 21-17 21-17.
The men's and women's beach volleyball semi-finals take place on Monday.
In the other two quarter-finals, United States duo Kerri Walsh and Misty May recorded a 21-19 21-14 win over Canada's Guylaine Dumont and Annie Martin.
And Australia's Natalie Cook and Nicole Sanderson completed the line-up with a 21-16 14-21 15-12 victory over Lucilla Perrotta and Daniela Gattelli of Italy.
In the men's event, Brazilians Emanuel Rego
and Ricardo Santos saw off the challenge of Swiss brothers Martin and Paul Laciga with a comfortable 21-13 21-16 to reach the semi-finals.
The Brazilians have been pitted against another Swiss pair, Patrick Heuscher and Stefan Kobel.
Heuscher and Kobel beat 12th seed Americans Dax Holdren and Stein Metzger 21-16 21-19.
Meanwhile, Spain's Javier Bosma and Pablo Herrera will face Australia's Julien Prosser and Mark Williams after they battled from one game down to beat John Child and Mark Heese 22-24 21-19 18-16.
The Australians ran out 15-10 21-19 16-21 winners over Andreas Scheuerpflug and Christoph Dieckmann of Germany.