Real Madrid boss Jose Mourinho says they must be prepared for anything on Monday at Barcelona.
Madrid lead the way with a one-point advantage over Barca after 12 rounds, with Mourinho well on the way to giving Los Merengues a more attacking style of play.
He bought young talent in the shape of Mesut Ozil, Sami Khedira and Angel Di Maria over the summer with the only downside their relative lack of experience in big domestic matches and a shortage of time to gel, a point Mourinho acknowledges.
He told AS: "You never know how the team will react.
"Physically we are fine and know what to do, but we face a team that has had a lot of time working together and we have only had a few months.
"But, in any case, we must be prepared for any eventuality."
Mourinho has enjoyed great success throughout his coaching career by building strong, resolute sides which are hard to beat.
And he has followed this path once more at the Bernabeu, albeit with a greater amount of flair going forward.
He added: "It's very important the coach has a clear idea of what he wants: how to play, how to work each day.
"It is one thing to admire someone but something else to copy them.
"You must learn from people who have been successful while always keeping your own personality."
