The Atletico legend is optimistic about his old side's chances, even though the club have failed miserably against los Blancos in recent times
Aragones, who made over 350 appearances for Atleti during his playing career and enjoyed four spells as the club's head coach, is backing the Argentine to mastermind a first victory over los Blancos since 1999.
"Simeone knows how to beat Real Madrid. He has given Atletico something extra and really motivates them. He was already like that as a player. You cannot do any better than him when it comes to results," Aragones told Marca.
"Atletico face a difficult task because Real are a great team. That Atletico haven't beat them for such a long time makes things even more complicated mentally. It will be tough beat them, but Simeone will find a way.
"There's a big difference between both teams when it comes to financial resources. That's always been the case, though, and Atletico have still won trophies in the past. It's not all about money in football."
Friday's match at the Santiago Bernabeu kicks off at 21:30CET.