Martin Klizan saved match points on his way to the Brasil Open second round, while defending champion Federico Delbonis bowed out on Tuesday.
Klizan overcame fellow left-hander Thomaz Bellucci 5-7 6-3 7-5 at the ATP 250 event played on clay courts in Sao Paulo.
The Slovakian eighth seed had looked in serious trouble when he fell 5-2 behind in the deciding set.
But Bellucci's break of serve was squandered in the ninth game, the Brazilian wasting two match points in the process.
Klizan would win the final five games of the match, breaking crucially in the 11th game on his way to victory.
Wildcard Joao Souza is Klizan's next opponent after the Brazilian beat Spaniard Pablo Carreno Busta 6-2 7-6 (8-6).
Delbonis was a surprise champion in 2014, but there will be no repeat after he went down to Argentine countryman and lucky loser Facundo Bagnis 6-3 2-6 6-4.
Bagnis broke once in the first and third sets on his way to victory in one hour 57 minutes.
Uruguayan fifth seed Pablo Cuevas awaits in the second round.
Fernando Verdasco did what was expected of him, cruising past Maximo Gonzalez 6-2 6-3.
The Spanish seventh seed will face Dusan Lajovic after the Serbian fought his way past Pablo Andujar 3-6 6-3 6-2.
It was a good day for the seeds, with Santiago Giraldo also advancing.
The Colombian sixth seed overcame Belgian wildcard Kimmer Coppejans 7-5 7-6 (7-4) to set up a meeting with Carlos Berlocq.
Berlocq won an all-Argentine affair against Guido Pella, beating the qualifier 6-4 7-6 (7-4).
Last year's runner-up Paolo Lorenzi exited, suffering a 7-5 6-4 loss to Diego Schwartzman.
Dutchman Thiemo de Bakker also progressed, needing almost three hours to battle past Juan Monaco 6-7 (5-7) 7-6 (7-4) 6-4.