Cameron Norrie began his Rio Open title defence with a straight-sets win over Hugo Dellien that left him “dripping sweat”.
The British No. 1 seemed to triumph comfortably, 6-3 6-2, but denied that it had been a routine victory against the Bolivian.
“Good sensations, good feelings on this court,” Norrie said. “You said it was pretty straightforward, but I was absolutely dripping sweat. So it’s never easy out here.”
Norrie, seeded second behind Carlos Alcaraz in Brazil, will face Chile’s Tomas Barrios Vera in the second round.
Norrie saved the only break point he faced against Dellien and took three of his seven opportunities against the Bolivian’s serve.
He wrapped up the win in 82 minutes and was pleased with his efforts.
“I think I managed my service games really well,” Norrie added.
“I served much better than last week [against Coria] and I was a bit more patient and knew I had to play point for point and really make the rallies a bit longer.
“I think I learned from last week with that, and just happy to be back in Brazil.”
Fourth seed Francisco Cerundolo also progressed, beating fellow Argentine Francisco Comesana to set up a tie against Albert Ramos-Vinolas.
Home favourite Thiago Seyboth Wild booked a spot in the second round by beating Alejandro Tabilo in three sets and will face Jaume Munar next.
In Mexico, Dan Evans defeated fifth seed Roman Safiullin 6-2 6-4 to reach the second round of the Los Cabos Open.
But hopes of an all-British tie were dashed when Jack Draper fell to a 4-6 7-6(5) 6-4 defeat to Thanasi Kokkinakis, who will face Evans next.