"He's young and he still has a lot of things to do yet in football," the 36-year-old told Sky Sports.
"He still has a lot of things to do at Real Madrid and I don't know if he wants to move or not, even if another team wants him. In football, we never know.
"It's not easy to stop him. For me he is one of the best that I've ever seen and it's very hard to stop him if he has a good day.
"I'm glad that he's Portuguese and that I don't have to play against him."