Real Madrid president Ramon Calderon says any move for Manchester United star Cristiano Ronaldo will be sparked by the Portuguese ace.

"The players play where they want. If a player decides to leave he is unstoppable, slavery was abolished a long time ago, nobody can prevent a player from moving," Calderon was quoted as telling Punto Radio.

"If the player is firm in his decision there is no one who can hold him back."

He added: "I have always said that if Manchester want to sell him, we will ask about him, and if he wants to come and we can pay what they ask."