The Portuguese superstar joined Real Madrid for a world record £80million this summer.
“He may come back, you never know,” said Ferguson. “Sometimes it happens that way.
“He loved United. If you look back at the six years he had with us, he never missed training.
“That’s one of the things he has above all other players – he was never injured, he always played.
“And his best is yet to come. He is only 24.”
“Cristiano is a massive loss,” Fergie added.
“I have nothing but praise for the boy. He is easily the best player in the world.
“He is better than Kaka and better than Messi. He is streets ahead of them all.
“His contribution as a goal threat is unbelievable. His stats are incredible. Strikes at goal, attempts on goal, raids into the penalty box, headers. It is all there. Absolutely astounding.”
