Former Moselle Open winner David Goffin came from a set down to beat Nicolas Almagro and advance to the quarter-finals, as defending champion Lucas Pouille crashed out.
Having received a bye through to the second round, number two seed Goffin made a sluggish start to his first match at the ATP 250 event, perhaps as a consequence of his exertions for Belgium in a Davis Cup semi-final triumph over Australia last weekend.
The world number 12, who lifted the trophy here in 2014, eventually asserted himself, beating his Spanish opponent 3-6 6-3 6-3 after one hour and 33 minutes on indoor hard courts in Metz.
After Richard Gasquet and Gilles Simon bowed out in the first and second round respectively, there were more French casualties on Thursday, although one was a victim of friendly fire.
Marius Copil won two tie-breaks to upset third seed Pouille 7-6 (7-4) 7-6 (8-6), while Kenny De Schepper ended the challenge of Nicolas Mahut, beating his fellow Frenchman 6-4 7-5.
-- Marius Copil (@MariusCopil) September 21, 2017
Nikoloz Basilashvili sprung a surprise to dump out fourth seed Gilles Muller 6-4 6-4.
Benoit Paire was among those domestic representatives to advance to the last eight courtesy of a dominant, straight-sets win over Spain's Marcel Granollers.
Denis Istomin battled to a three-set victory over lucky loser Yannick Maden, while Mischa Zverev, beaten finalist in 2010, took care of Henri Laaksonen in straights.