World number one Novak Djokovic suffered a quarter-final exit against Russian Daniil Medvedev at the Monte Carlo Masters.
The 31-year-old, winner of the event in 2013 and 2015, lost to the world number 14 in two hours, 20 minutes.
Medvedev faces another Serb in the last four, world number 48 Dusan Lajovic.
Defending champion Rafael Nadal, seeking an unprecedented 12th Monte Carlo title, plays Argentine world number 35 later on Friday.
Djokovic won a record seventh Australian Open title in January but lost in the third round at Indian Wells and the fourth round in Miami last month.