Defending champion David Ferrer advanced to the semifinals of the Copa Claro clay-court tournament on Friday with a 6-2, 6-1 victory over Fabio Fognini of Italy.
The top-seeded Ferrer will face fellow Spaniard Tommy Robredo, who beat Julian Reister of Germany 6-3, 6-2.
"It will be tough match," Ferrer said. "Each time I have played Tommy it has been a close match and I will have to play at my best to beat him."
Ferrer holds a 5-2 edge in head-to-head matches, and has won the last two.
It could be all-Spanish semifinals in the Argentine capital.
Second-seeded Nicolas Almagro of Spain played later against Federico Delbonis of Argentina, and No. 3 Stanislas Wawrinka of Switzerland was up against Albert Ramos of Spain in the other quarterfinal.
With his No. 4 ranking, Ferrer is a strong favorite to win his second tournament of the season. He won the Heineken Open last month in Auckland, New Zealand.
Rafael Nadal skipped this event on his Latin American tour, after making his comeback from a long-term knee injury by playing in Chile and Brazil. He will play next week in Acapulco, Mexico.