Cristian Garin cruised into the Cordoba Open quarter-finals, while Guido Pella bowed out after a three-hour marathon on Wednesday.
Garin, the third seed at the ATP 250 event played on clay, rushed past Hungarian Attila Balazs 6-3 6-0 in just 68 minutes in Argentina.
The Chilean incredibly lost just eight points on serve, while converting five of 16 break points in a dominant performance.
Garin will face Uruguayan sixth seed Pablo Cuevas, who survived a test to get past Italian Gianluca Mager 6-7 (5-7) 7-6 (7-2) 6-1.
Pella, the second seed and last year's runner-up, fell to Frenchman Corentin Moutet after a gruelling contest.
Moutet beat Pella at the French Open last year and he repeated the feat courtesy of a 6-7 (4-7) 7-5 6-3 victory after just over three hours on court.
Slovakian Andrej Martin will face Moutet after overcoming Spanish qualifier Carlos Taberner 6-3 7-6 (9-7).