Second seed Stefanos Tsitsipas and third seed Daniil Medvedev failed to reach the last four of the ATP Monte-Carlo Masters on Friday, leaving all top four seeds out of the tournament.

World no.1 Novak Djokovic of Serbia and fourth-seeded Norwegian Casper Ruud had suffered early exits in the round of 16 a day earlier at the first clay-court Masters tournament of the season.

American Taylor Fritz ended defending champion Tsitsipas' 12-match winning streak with a 6-2, 6-4 victory in only 70 minutes.

Fritz struck 21 winners, and was dominant on serve as he clinched his first win against Greece's Tsitsipas. He will next face Russia's Andrey Rublev, who ended German qualifier Jan-Lennard Struff's fairy-tale run with a 6-1, 7-6 (5) win.

"I thought my level today was very high. I think I played a very good match. Beating him here gives me a lot of confidence," Fritz said. "It has given me the reassurance I need to know I can play well on clay."

Denmark's Holger Rune, 19, defeated Russia's Medvedev 6-3, 6-4 to set up his second Masters semifinal with seventh seed Jannik Sinner, who knocked out fellow Italian Lorenzo Musetti 6-2, 6-2.

(With input from Xinhua)