Sao Paulo: Spain's Rafael Nadal scored an easy two-set victory in his singles debut at the Brazil Open late on Thursday. (Agencies)
The former world number one needed only 78 minutes to prevail over Brazilian Joao Souza, ranked 101st in the world 6-3, 6-4.
Nadal advanced to the quarterfinals which will be played on Friday.
"It was an important victory for me," Nadal said. "The conditions are very difficult. The court is very fast, the ball too."
Asked about his injured left knee, he replied: "I think it was acceptable, normal. Let's hope it will be the same on Friday. The important things is that it (the knee) does not hurt."
On wednesday, the Spanish star withdrew from a scheduled doubles match he was to have played with Argentina's David Nalbandianagainst Argentine Horacio Zeballos and Austrian Oliver Marach, citing "knee overuse".
Nadal, currently ranked number five in the world, only returned to the tour in Chile last week after a seven-month injury absence.
The 11-time grand slam champion, who lost both the singles and doubles finals on Sunday at his comeback event in Vina del Mar, Chile, is the top seed at this week's event.
The USD 455,775 Brazil Open is part of the Latin American clay court circuit, along with the Vina del Mar and the Mexico Open in Acapulco where Nadal plans to play later this month.
Sao Paulo: Spain's Rafael Nadal scored an easy two-set victory in his singles debut at the Brazil Open late on Thursday.