American Taylor Fritz upset two-time defending champion Stefanos Tsitsipas 6-2, 6-4 to reach the Monte Carlo Masters semifinals Friday.
Second-seeded Tsitsipas was on a 12-match winning streak on the French Cote d’Azur, where he claimed his two Masters 1000 titles.
“I stuck to the strategy of pulling the trigger and not letting him dictate with his forehand,” said No. 8 seed Fritz, who is still seeking his first career title on clay.
Tsitsipas broke back to 4-4 in the second set, but Fritz broke his serve easily for 5-4 and closed out the match with an ace for a love hold to reach the semifinals of a Masters event for the first time.
“I just seemed off,” Tsitsipas said. “My serve was not working very well today, and against opponents like Taylor you have to serve well. I was aware of that during the match. I just couldn’t find the rhythm. I am much better than this, and I’m disappointed I was not able to show my game today.”
Fritz will next face fifth-seeded Andrey Rublev of Russia, who beat German qualifier Jan-Lennard Struff 6-1, 7-6 (5).
In the other half of the draw, Denmark’s Holger Rune tormented No. 3 seed Daniil Medvedev with passing shots and drop shots to advance with a 6-3, 6-4 victory.
The 19-year-old Rune, who proved a sensation at last year’s French Open when he reached the quarterfinals, dropped only six points on serve in the opening set and converted his only break chance in the second.
“I have huge respect for everything he’s done,” Rune said of Medvedev. “It was not easy to stop him, but I’m happy I managed to do it.”
He will next meet Jannik Sinner, who defeated Lorenzo Musetti 6-2, 6-2 in an all-Italian quarterfinal. The seventh-seeded Sinner saved all five break points he faced against Musetti in reaching his third straight semifinal at Masters level this season.
“I felt great today on the court,” Sinner said. “I’m hitting the ball in the right spots in the right moments. I tried to stay aggressive, which I’ve done.”
Sinner broke Musetti twice in the second set and converted his first match point with a strong first serve that Musetti returned long.
The Associated Press and Reuters contributed to this report.