Berlocq cruised to 6-2, 6-1 victory over Russian Andrey Kuznetsov on the clay courts of Vina del Mar, joining Frenchman Guillaume Rufin, 16-year-old Chilean wild card Christian Garin and Argentine Horacio Zeballos among the Day 2 winners.
Also recording a first-round victory Tuesday was 2011 winner Tommy Robredo, who dispatched fellow Spaniard Pere Riba 6-2, 6-2.
Nadal, who has been out of action with a knee injury since June, returned to the court in a doubles match with teammate and defending Vina del Mar champion Juan Monaco.
They bested the duo of Frantisek Cermak and Lukas Dlouhy 6-3, 6-2.
Nadal had a first-round bye in the single competition. He was set to take on qualifier Federico Delbonis Wednesday.