Mendieta, who took part in the contest while on loan at Barcelona in 2002-03, insists that it is the biggest game in club football because of the atmosphere and talent involved.
"I think that it is the best game that you could possibly play in," he told Goal.com.
"I played in the Rome but for me the Clasico is the most amazing derby there is.
"That is because of the type of football that is played. It is also because of the electric atmosphere at the games. It is so good it is almost indescribable."
Barcelona host Real Madrid at the Nou Camp this weekend.