Madrid see Illarramendi as a replacement for Xabi Alonso.
Prieto said: "At the moment, we don't know anything, but the club has already made it clear that if they want to buy Illarramendi, they'll have to pay his release clause. And it seems that Real Madrid are willing to pay it."
"For the moment, he is a Real Sociedad player; we're talking about a hypothetical situation. We'll respect his decision."