Open 13 Marseille top seed Daniil Medvedev got his tournament off to a fine start as he came from behind to defeat NextGen champion Jannik Sinner.
The 18-year-old Sinner claimed the first top-10 scalp of his career when he beat David Goffin last week, but he did not have enough to hold on against Medvedev.
After world number five Medvedev was brushed aside in a 25-minute first set, the Russian claimed two vital breaks in the second set before taking the decider for a 1-6 6-1 6-2 victory.
Medvedev will next take on Gilles Simon - a Marseille champion in 2007 and 2015 - after the Frenchman overcame Aljaz Bedene 7-6 (8-6) 6-4 to reach the quarterfinals.
Meanwhile, Goffin suffered another upset, going down 6-4 7-6 (7-5) to Belarusian qualifier Egor Gerasimov.
Gerasimov's next opponent, Felix Auger-Aliassime, overcame Pierre-Hugues Herbert in a thrilling encounter, with the youngster coming out on top 6-0 6-7 (6-8) 7-6 (11-9).
Auger-Aliassime's Canadian compatriot Denis Shapovalov also made the last eight as 17 aces helped him defeat two-time finalist Marin Cilic 6-4 4-6 6-2, with the world number 15 to meet Alexander Bublik next.
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