The top-seeded Andreev will next play sixth-seeded Marc Gicquel of France, who beat Mischa Zverev of Germany 6-4, 7-5.
Gicquel broke Zverev at 5-5 before converting his third match point with a forehand winner down the line. Zverev wasted five break points in the first set.
Florent Serra of France also advanced. The fifth-seeded Serra defeated Olivier Rochus of Belgium 6-3, 6-3 and will next face Teimuraz Gabashvili of Russia, who beat Ruben Ramirez Hidalgo of Spain 6-4, 6-4.
Montanes, Ferrero, Gil reach Casablanca quarters
Ferrero beats Andreev to reach Casablanca final
