The scores in the victory over his Algerian opponent were 7-5, 7-6 (7-2).
Other winners were second-seeded Jose Acasuso of Argentina; unseeded Albert Montanes of Spain, who led seventh-seeded Nicolas Massu, 6-1, 2-1, when Massu was forced to retire due to an abdominal injury; and No. 8 seed Paul-Henri Mathieu of France.
Massu was beaten by Italian Daniele Bracciali in last year's final.
Friday's quarterfinals will pit the top-seeded Hrbaty against Montanes, Acasuso against Mathieu, third-seeded Julien Benneteau of France against No. 5 and fellow Frenchman Marc Gicquel, and Ruben Ramirez Hidalgo of Spain will play Frenchman Sebastien Grosjean, the 2000 Casablanca runner-up.
Video of Victoria’s Secret models trying to 'twerk' hits Instagram
Workers accuse National Zoo of animal mismanagement