It was at least a test for the six-time champion, who won 7-6 (7/4) 6-2 6-3, after he had lost only 19 games in his first five matches and reeled off 17 straight games in beating Juan Monaco in the fourth round.
He'll now face an all-Spanish affair against David Ferrer.
"In all the tournaments where I made it to the quarter-finals or semi-finals, when I went deep in the tournament, I needed to have a very powerful serve," said Nadal.
"This year my serve is working very well, and I've managed to turn matches around. I have lost my serve, but on very few occasions.
"I managed to win the most difficult points and I had a very good serve. When you serve a winner, then it's perfect. At the moment, everything is fine."
In the womens' half of the draw, Petra Kvitova is hoping to show her fighting spirit in her semi showdown with Maria Sharapova.
The Czech, defeated Yaroslava Shvedova 3-6, 6-2, 6-4, while Sharapova managed to dispose of Kaia Kanepi in straight sets 6-2, 6-3.
Sam Stosur will face Sara Errani in the other semi after they saw off Dominka Cibulkova and Angelique Kerber, respectively.
