Nadal, the four-time defending champ who had a first-round bye, has beaten Chela in four of five matches, including all three on clay. Nadal's lone defeat to Chela came five years ago on hard courts in Cincinnati.
"Chela is a good clay-court player. I have to play good tennis if I want to have good chances to win," Nadal said. "[I need to] try to play aggressive without a lot of mistakes."