Thomaz Bellucci advanced to the Ecuador Open quarter-finals on Wednesday, while defending champion Victor Estrella Burgos won his opener.
Bellucci, runner-up at the ATP 250 event last year, edged Serbian wildcard and former world number eight Janko Tipsarevic 7-6 (10-8) 7-6 (7-2).
Brazilian fourth seed Bellucci next faces eighth seed Renzo Olivo after the Argentinian beat Santiago Giraldo 7-6 (7-3) 2-6 6-3 on the clay in Quito.
Estrella Burgos, the only man to have won the tournament after successes in 2015 and 2016, started his campaign with a win.
The veteran world number 156 overcame Andrej Martin 3-6 6-2 6-4 in one hour, 52 minutes.
Estrella Burgos will face top seed Ivo Karlovic in the second round.
The second-seeded Albert Ramos-Vinolas advanced to the last eight with a 6-2 7-5 win against qualifier Alejandro Falla.
Awaiting him in the quarters is Roberto Carballes Baena, who ended the career of Giovanni Lapentti with a 6-3 6-4 win.
In emotional scenes after his loss, retiring 34-year-old Lapentti was in tears before being honoured in an on-court presentation.