Metz - Second seed David Goffin eased into the ATP Metz Open quarter-finals but French third and fourth seeds Lucas Pouille and Gilles Simon were made to struggle on Thursday.
Pouille, the world number 18, needed almost two hours to see off his world number 112 ranked compatriot Pierre-Hugues Herbert 6-4, 6-7, 6-4.
He next faces French wildcard and world No 233 Julien Benneteau.
Simon was also pushed to a decider by Spain's Guillermo Garcia-Lopez.
World No 28 Simon eventually prevailed 6-7, 6-3, 6-4 and will next face Tunisia's Malek Jaziri, who ousted Frenchman Vincent Millot 4-6, 6-3, 6-3.
ATP Metz Open second round results on Thursday (x denotes seeding):
Gilles Simon (FRA x4) bt Guillermo Garca-Lpez (ESP) 6-7 (5/7), 6-3, 6-4
Malek Jaziri (TUN) bt Vincent Millot (FRA) 4-6, 6-3, 6-3
Lucas Pouille (FRA) bt Pierre-Hugues Herbert (FRA) 6-4, 6-7 (6/8), 6-4
David Goffin (BEL x2) bt Jan-Lennard Struff (GER) 6-4, 6-2
Nicolas Mahut (FRA x8) bt Illya Marchenko (UKR) 6-3, 6-4