World number one Novak Djokovic was knocked out of the Monte Carlo Masters after falling to a three-set defeat by Italian 16th seed Lorenzo Musetti.
Musetti will face fellow Italian Jannik Sinner who came back from a set and match point down to beat Hubert Hurkacz to reach the quarter-finals.
Seventh seed Sinner, a Monaco quarter-finalist last year, beat the Pole 3-6 7-6 (8-6) 6-1.
Defending champion Stefanos Tsitsipas beat unseeded Chilean Nicolas Jarry 6-3 6-4 in his last-16 match.
However, fourth seed Casper Ruud was stunned by German qualifier Jan-Lennard Struff earlier on Thursday.