Media speculation in Spain continues to link Real Madrid with Ronaldo, who has enjoyed a remarkable season with the Red Devils, who could yet complete a Premier League and Champions League double.

But while the Spanish press might be optimistic about a successful swoop for Ronaldo, Heinze, who knows the Portugal winger well from his time at United, is less convinced about his former team-mate moving to the Bernabeu anytime soon.

"I talk with him (Ronaldo) all the time and I tell him how great this club is and the nice things that Madrid has, but I know that is very difficult for him to come because he has a coach who had trust in him when he was younger," Heinze told Radio Marca.

"Whilst Ferguson is at United it is very difficult. He is a fundamental part of their plans."