"An achievement like this seemed impossible only a short time ago. It is a dream for everyone here," Sky Sports News quotes Isco as saying.
"We came out of the blocks with a lot of intensity because that is what this tie demanded of us. We then settled into the match and showed what we were capable of."
Roque Santa Cruz, who came on as a substitute to net Malaga's second goal, added: "I think that this group of players and the fans deserved this.
"The friendship and closeness within the squad is fundamental. I am happy to have scored, and for the fact we won."
The draw for the quarter-finals takes place on Friday, March 15.