Metz - Nicolas Mahut of France has upset third-seeded Andreas Seppi of Italy 6-4, 6-4 to reach the Moselle Open quarter-finals on Thursday.
Mahut broke last year's runner-up twice in each set.
The Frenchman won two titles in the summer and is enjoying his best season.
Frenchman Gilles Simon and German duo Florian Mayer and Benjamin Becker have also advanced to the last eight.
The second-seeded Simon cruised past compatriot Kenny De Schepper 6-2, 6-3, while the eighth-seeded Mayer did not face any break points in his 6-3, 6-2 victory over Lukas Lacko of Slovakia, and Becker outlasted French wild card Albano Olivetti 6-7 (8), 6-3, 6-1.
Simon, a 2010
champion, jumped to 4-0. De Schepper raised his game in the second set
but failed to convert two break points.
Simon broke serve for a 4-3 lead before clinching the victory when De Schepper's forehand went wide.
254th in the world, Olivetti rallied from 6-2 down in the tiebreaker to
win the opening set.
But Becker broke Olivetti twice in the next set to
even the match.
The German took leads of 3-0 and 5-1 in the third set.
Results from the fourth day of the ATP Metz Open on Thursday (x denotes seeding):
Florian Mayer (GER x8) bt Lukas Lacko (SVK) 6-3, 6-2
Benjamin Becker (GER) bt Albano Olivetti (FRA) 6-7 (8/10), 6-3, 6-1
Nicolas Mahut (FRA) bt Andreas Seppi (ITA x3) 6-4, 6-4
Gilles Simon (FRA x2) bt Kenny De Schepper (FRA) 6-2, 6-3