Unseeded Gregoire Barrere of France upset fourth seed Grigor Dimitrov 6-7(4) 6-4 7-5, saving seven break points in the process.
The 25-year old Frenchman needed two hours and 34 minutes to defeat the World No.23, and he next faces the winner between Sweden's Mikael Ymer and seventh seed Filip Krajinovic.
Third seed Denis Shapovalov lost to compatriot Vasek Pospisil 2-6 3-6, and the Canadian now faces the winner between Spain's Feliciano Lopez and France's Richard Gasquet in the quarterfinals.
Gasquet faced countryman Gilles Simon, defeating his good friend 6-4 6-4 in an hour and 27 minutes. The three-time former champion looks to add a fourth title at Montpellier, having won 25 of his 30 matches there.
Feliciano Lopez cruised past eighth seed Ugo Humbert 6-4 6-1 in just over an hour. Lopez won an astonishing 92% of his first serve, and saved both break points faced.
Adrian Mannarino also made it to the quarterfinals, overcoming Australian Alexei Popyrin with the unusual score of 6-0 6-7(7) 6-0. The World No.45 breaks a three-match losing streak, but next faces top seed Gael Monfils in the quarterfinals.
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