Top-seeded David Ferrer defeated fellow Spaniard Albert Ramos 6-1, 6-2 to reach the semifinals of the Copa Claro ATP tournament.
Second-seeded Fabio Fognini of Italy and third-seeded Tommy Robredo of Spain also advanced into last four Friday, setting up a semifinal matchup, reports Xinhua.
Ferrer will next face fellow Spaniard Nicolas Almagro, the fourth seed, who defeated Jeremy Chardy of France 7-6 (7), 6-3 in another quarterfinal match.
Fognini, who won the ATP event last week in Chile, advanced by defeating Pablo Andujar of Spain 6-4, 6-3.
Robredo advanced when Robin Haase of the Netherlands retired with a back injury while trailing 6-1, 2-0.
Ferrer, the two-time defending champion in Buenos Aires, is aiming to win his 21st ATP tournament.