Top-seeded Tomas Berdych struggled past Ernests Gulbis of Latvia 6-4, 6-7 (10), 6-4 to reach the quarterfinals of the Open 13.
Berdych withstood 19 aces from Gulbis in his second-round opener.
He was joined by third-seeded Jo-Wilfried Tsonga, the 2009 champion who eased past Nikolay Davydenko 7-6 (1), 6-3.
Tsonga will meet Bernard Tomic of Australia, who also won in straight sets, 6-3, 7-5, against Somdev Devvarman of India.
Gilles Muller, who upset fifth-seeded Richard Gasquet in the first round, defeated Marcel Granollers 7-6 (2), 7-6 (1).
Sixth-seeded Gilles Simon won his first-round match beating Robin Haase of the Netherlands 7-5, 7-5.
Also advancing were fellow Frenchman Julien Benneteau, and Russia's Dmitry Tursunov.