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.
The second-seeded Simon cruised past Kenny De Schepper 6-2, 6-3, while the eighth-seeded Mayer did not face a break point in his 6-3, 6-2 victory over Lukas Lacko of Slovakia. Becker outlasted French wild card Albano Olivetti 6-7 (8), 6-3, 6-1.
Simon, a 2010 champion, took a 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 win when De Schepper's forehand went wide.
Ranked 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.