Roddick, seeded sixth, fired 17 aces en route to a 7-6 (7-5), 6-2 win over Nadal and drew a semifinals match with Novak Djokovic, who lived up to his No. 3 seed with a 6-2, 6-1 rout of Igor Andreev in his quarterfinal match.
Friday's other semifinal has fifth-seeded Nikolay Davydenko going against unseeded Feliciano Lopez. Lopez had the second-biggest upset of the quarterfinals, taking out No. 4 David Ferrer, 6-3, 6-3. Davydenko was a 7-5, 6-4 winner over Andy Murray Thursday.
Roddick made news off the court, too, announcing that Jimmy Connors was no longer his coach. He said Connors left Team Roddick last week. They had worked together about 18 months.
"I think it was tough for him to do it part time, maybe not getting exactly the results we wanted ... It was amicable," Roddick said of the break with Connors.
"We're friends. I have so much respect for him as a person. I'm sad but thankful for what he was able to give to me and that he could take time out of his retirement and spend it with me."