Zinedine Zidane’s men take on Bayern Munich at the Bernabeu tonight in the second-leg of their Champions League quarter-final.
Madrid hold a 2-1 advantage over their German opponents but they will be without star man Gareth Bale this evening.
The Welshman suffered a calf problem in last week’s trip to the Allianz Arena and Zidane now faces the difficult task in choosing his replacement.
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Isco has been tipped to take up the position in the starting XI but Zidane hasn’t revealed who will fill Bale’s boots.
Asked if Isco had earned his place, Zidane said: “Like all of the others, he's ready. We are prepared to play this game. I will decide who will play.
"I have already decided but I can't say any more than that. All of the players are doing great. I have to choose one.
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“But I am very happy that they are all at a high level and that makes it it even more difficult for me to select the team but it's better that way”.
Bale also faces a race against time to be fit for El Clasico on Sunday (7.45pm) when they host Barcelona.
“I hope he's back in time, but I can't be completely sure. We'll see how he is day by day,” Zidane added.
Madrid lead Barca by three points at the top of La Liga and have a game in hand.