Perotti scored in the 43rd minute at Sanchez Pizjuan stadium, getting behind the defense to tap in a low cross from Jesus Navas at the far post.
Jiri Jarosik leveled for Zaragoza in the 47th, heading a free kick inside the near post. But Kanoute scored from the penalty spot in the 55th after Leonardo Ponzio had fouled Martin.
Negredo converted a spot kick in the third minute of injury of time when Paulo Da Silva fouled him in the area.
Also, it was: Real Sociedad 1, Hercules 3; Espanyol 1, Racing Santander 2; Levante 3, Malaga 1 and Deportivo La Coruna 2, Mallorca 1.