Defending champion Gael Monfils finished off Michael Russell of the United States with his 17th ace in winning 6-3 6-3 to reach the quarter-finals of the ATP event in Montpellier on Thursday.

Russell double-faulted to drop serve at 3-3 and lost the opening set on a forehand error. The third-seeded Monfils capitalised on a backhand error from Russell to break for a 3-1 lead in the second set.

The top-seeded Tomas Berdych cruised past French qualifier Florent Serra 6-0 6-2 in another second-round match.

Berdych broke Serra five times to set up a match against Nicolas Mahut of France, who beat sixth-seeded Florian Mayer 7-6 (7-3) 6-3.

Mahut jumped out to 4-1 in the tiebreaker and took the first set when Mayer double-faulted. He broke the German twice in the final set to clinch victory.

Seeded Frenchmen Gilles Simon and Richard Gasquet both won in straight sets on Wednesday to reach the quarter-finals.