Nadal, who has won three Grand Slam titles this year, beat Canada's Milos Raonic 6-4, 6-4. Second-seeded Roddick downed Frenchman Jeremy Chardy 6-4, 7-6 (4).
Story continues below ↓advertisement | your ad hereNadal's reward is to face Dmitry Tursunov of Russia in Friday's quarterfinals.
"For me, I did the things that I needed to do with the serve and return," Nadal said. "He is still very young. His serve is unbelievable, and there are things he can improve."
Roddick, ranked 10th in the world, is playing his first ATP tournament since losing in the second round of the U.S. Open. He served only five aces - to six for Chardy - but won 83 percent of his first serve points.
Roddick will play fifth-seeded Gael Monfils of France, who beat Italy's Andreas Seppi 6-4, 6-4. Monfils reached the semifinals here last year.
Viktor Troicki beat fifth-seeded Jurgen Melzer 7-6 (7), 3-6, 7-6 (3) for his first win over the Austrian, ranked 13th in the world. He now faces Guillermo Garcia-Lopez of Spain.
The fourth quarterfinal pits Finland's Jarkko Nieminen against Radek Stepanek of the Czech Republic.
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Nadal set for Mallorca roleUnseeded Lu upsets Roddick in 5-set marathon
