Nadal will face off in Saturday's semi-final against another Argentine, Martin Alund, who defeated Filippo Volandri of Italy 7-5, 7-6 on Friday.
The Spanish star is top seed in the $455,775 Brazil Open, his second comeback event after a seven-month absence due to a knee injury.
Last week, he competed in the Vina del Mar Open in Chile, losing the singles and doubles finals on Sunday.
The world number five, who has claimed seven of his 11 Grand Slam titles on the clay courts of Roland Garros, won the Brazil Open in 2005 when it was held in Costa do Sauipe in eastern Bahia state.
The tournament was moved to Sao Paulo last year when Spaniard Nicolas Almagro won.