Pella took the match 4-6, 6-1, 6-2 in one hour and 51 minutes to advance to the round-of-16 of the ATP 250 clay-court event on Tuesday, reports Xinhua news agency.
In the next round, the 27-year-old will face Chile's Nicolas Jarry, who overcame Serbia's Dusan Lajovic 6-4, 1-6, 7-5.
The upset of the day was the straight-set victory of local veteran Rogerio Dutra Silva over American seventh seed Tennys Sandgren.
The 34-year-old, who is currently ranked 106th in the world, needed just an hour and 11 minutes to breeze past Sandgren 6-0, 6-4.
Thursday's schedule includes a clash between Italian second seed Fabio Fognini and Portuguese qualifier Joao Domingues while third seed Pablo Cuevas of Uruguay will face Austrian Sebastian Ofner.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
