Cilic will meet Novak Djokovic in Sunday's title match.
It was the first meeting between Cilic and Nadal, a six-time major champion who began the year ranked No. 1 in the world. Nadal had won all of the eight previous matches he had played in this event.
Cilic will be trying for his third tournament victory of the year and the fourth of his career. His most recent title came in February in his native Croatia.
Djokovic, seeded third, coasted past Robin Soderling 6-3, 6-3 in the other semifinal match. Djokovic has defeated Cilic in all three of their meetings.
Nadal also suffered semifinal losses in his two previous tournaments -- one of them a setback against eventual champion Juan Marin Del Potro at the U.S. Open.
Copyright 2009 by United Press International.