Speaking after the match, the 26-year-old said: "My physical performance needs to improve. My movements need to improve.
"After seven months out I don't want to take crazy risks but when I am playing in a tournament my mentality is to try my best in every moment. I am satisfied to be in the next round. That's the most important thing.
"The victory is important because it gives me the chance to play another day and I need to play matches and compete. Two weeks ago I didn't really know if I would be here playing. I am happy to be here. It was a good victory against a good opponent."
Nadal will face Leonardo Mayer in the next round.