The former Real Madrid attacker believes that his compatriot will bounce back from his difficult period at the Primera Division leaders
The Chile international has been criticised in recent weeks thanks to his relatively poor performances this season, but his compatriot has little doubt that his slump is only temporary.
"Everybody in Chile feels that he is an extraordinary player and believes he will resurface again at some point," Zamorano told Marca.
"Alexis is a great player who always does his utmost for the team. He will never let down his team-mates or not give his all. Every player goes through a difficult period at some point in his career.
"I went through a similar slump during my time at Real Madrid. I failed to find the net for three months or so. And I was a striker, whereas Alexis generally acts on the wing."
The 24-year-old Sanchez has made 13 La Liga appearances this season without scoring.