Top-seeded Nicolas Almagro of Spain stayed on course to win his second tournament in two weeks by beating Leonardo Mayer of Argentina 6-7 (3), 6-1, 6-3 to reach the Copa Claro quarterfinals on Thursday.
Almagro won the Brazil Open on Saturday for his eighth ATP title. All of his titles have come on clay _ the surface in Buenos Aires. Almagro will next face unseeded Argentinian Jose Acasuso, who rallied to defeat Pablo Cuevas of Uruguay 6-7 (2), 7-5, 6-1 in a 2-hours, 45-minute tussle.
In other second-round matches, third-seeded David Nalbandian of Argentina defeated countryman Juan Pablo Brzezicki 6-1, 6-2. He will face Spain's Tommy Robredo in Friday's quarterfinal. No. 6 Robredo defeated Albert Ramos-Vinolas of Spain 6-3, 7-5.
"Obviously he (Nalbandian) is the favorite and he has a lot of fans in this country," Robredo said. "When he plays well he is almost unstoppable."
Robredo won the Movistar Open earlier this month in Chile, another clay-court event.
In Friday's other quarterfinals, Juan Ignacio Chela plays Albert Montanes and Stanislas Wawrinka is up against Juan Monaco.