Spaniards Tommy Robredo and Pablo Andujar reached the quarter-finals of the Copa Claro on Wednesday.
Third seed Robredo came from a set down to beat Argentina's Guido Pella 4-6 6-1 6-4 at the claycourt event in Buenos Aires.
Andujar saw off his compatriot Marcel Granollers, the fifth seed, 6-3 6-0.
In Wednesday's first-round action, fourth seed Nicolas Almagro and eighth seed Jeremy Chardy both advanced in straight sets.
Ukraine's Alexandr Dolgopolov claimed a 6-3 4-6 7-6 (7/5) win over Pablo Cuevas of Uruguay, while Daniel Gimeno-Traver prevailed 7-5 6-2 in his all-Spanish affair with Ruben Ramirez Hidalgo.