MADRID, May 12 (Xinhua) -- Five-time champions Rafael Nadal lost to eighth-seeded Stefanos Tsitsipas of Greece 6-4, 2-6, 6-3 in the semifinals at the Madrid Open on Saturday, continuing his clay slump.

Second-ranked Nadal had beaten Tsitsipas in all of their three previous encounters, but the 20-year-old Greek played more aggressively this time. The two players won one set each before the young contender sealed the victory after winning the fourth match point in the decider, earning him a place in Sunday's final.

"It wasn't my best night," Nadal said after his third failure for a clay court title. "I knew what I had to do, it was clear to me, but I just wasn't capable of doing it."

Tsitsipas' thrilling victory means he has reached his fourth ATP final of the season. In Sunday's final, he will face reigning world no.1 Novak Djokovic of Serbia, who saw off Dominic Thiem of Austria 7-6 (2), 7-6 (4) to move closer to his third title of the year.