Ronaldo is struggling with a hamstring strain and could be absent for the Copa del Rey final against Barcelona.
"He's a big miss," said Casillas. We want him to get better as soon as possible.
"The cup final will be nice as it's against Barcelona and we want to win the title.
"With the goals he gives us and his presence, Cristiano imposes himself on the opponent and is important for us. He will know if he's going to be fit for the final. If he's better he will be the first to know."
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