Top seed Tommy Haas claimed a 7-6 (7/2) 6-3 win over Italy's Potito Starace to book his place in the quarter-finals of the Brasil Open.
Neither player could make an impression on the other's serve in the opening set, which the German took on a tie-break.
In the second, Haas began to assert his superiority against a player ranked 140 places beneath him and broke twice to ease into the last eight.
Nicolas Almagro's quest for a fourth title was ended as he went down to Federico Delbonis.
The champion from 2008, 2011 and 2012 took the first set but from there on in his Argentinian opponent took control and emerged a 3-6 6-3 6-2 victor.
He will next face Albert Montanes who moved into the quarter-finals after home wildcard Joao Souza withdrew from their match with the score at 6-4 2-3.
In the day's other game, Horacio Zeballos won the all-Argentinian clash with Guido Pella 6-3 6-4 to set up a clash with Haas.