Third-placed Barca visit the capital four points adrift of La Liga leaders Real in the race for the Spanish title.
The Catalan club claimed a 2-1 win in the reverse fixture at Camp Nou back in October, but Real have not lost a game in any competition since then - a run of 32 matches.
And Barca goalkeeper Valdes feels Gerardo Martino's men will need to play on the front foot in order to overcome their greatest rivals.
"We approach the Clasico with hope and a winning mentality, as always," Valdes said. "Because that is the only way you can win in (the) Bernabeu.
"We have to go there and take the control of the game, play directly, keep the possession of the ball and play offensively."
Valdes has made no secret of the fact he will leave Barca when his contract expires at the end of the season, with Manchester City, Liverpool and Monaco said to be interested in his services.
But the 32-year-old is keen to bow out in style, by helping the club secure a league double over Real in what is likely to be his final appearance at the Bernabeu.
"This Clasico is going to be my last game in Bernabeu as a Barcelona player," he added.
"I have a high respect for that stadium. It is an amazing place to play in because the fans give a lot of support to Real Madrid - especially in the Clasicos - and that makes playing there very special, even if you are in the other side.
"I would like to be able to say in a few days that we won because we really need those three points if we want to dispute the title against Real Madrid."
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