Real Madrid star Cristiano Ronaldo can't guarantee staying in Spain. The former Manchester United ace has been linked with a return to Old Trafford, along with Manchester City and Chelsea.

"To be honest, I don't know. In the future, nobody knows," Ronaldo told Sky Sports News HD.

"I feel very happy here, it is a great club with fantastic fans. It's great, but in the future nobody knows.

"I feel happy here but it one year or two, you never know. A man's head is always complicated, but at the moment I am very happy."