"I'm happy for this very positive start," said Nadal. "I had good feelings on court."
Nadal has not played competitively since pulling out of his semi-final against Roger Federer at the Indian Wells championships in March with a knee injury.
He completed his third victory in as many matches over Bautista Agut in 76 minutes and will face the unseeded Bulgarian Grigor Dimitrov in the last 16.
"I can't pretend to not have pain at all, but professionals normally play with pain," Nadal said. "It's part of the sport at the highest level and it's no limitations at all. I was able to move well and be confident with the things that I did."