Defending champion Diego Schwartzman has retired from the Rio Open because of a right leg injury.
The fourth-seeded Argentine trailed Uruguay’s Pablo Cuevas 6-1 4-1 when he stopped playing.
The first-round match began on Tuesday and was interrupted by rain.
Cuevas, the 2016 winner, will face Argentina’s Juan Ignacio Londero in the round of 16.
In second-round matches, Jaume Munar of Spain has beaten Cameron Norrie of Britain 7-6 (6) 5-7 7-6 (4), Bolivia’s Hugo Dellien has topped Roberto Carballes Baena of Spain 7-5 6-4 and Slovenia’s Aljaz Bedene has disposed of Thiago Monteiro of Brazil 6-3 6-4.