Sir Alex Ferguson has not ruled out the possibility of Cristiano Ronaldo returning to Manchester United in the future.
The Portugal international's much-anticipated transfer to Real Madrid was finally completed earlier this summer, but Ferguson insists the 24-year-old had an enjoyable time at Old Trafford.
"His best is yet to come because he's just 24," Ferguson was quoted as saying in the Guardian.
"I'll be very proud when I see him at his best because we had a part to play in it. He came to the right club at the right part of his career.
"He could have gone to Real Madrid or Barcelona as a boy but he came to the right club and he appreciates that.
"And he may come back, you never know. I don't see it happening if things go wrong at Real Madrid necessarily, but he loved Manchester United so it may happen.
"He loved the club. If you look at the six years he had with us, he never missed training and he was never injured. He always played. He was fantastic.
"It wasn't easy to see him leave. I had a good chat with the boy about it but he had made up his mind. Last year he was begging me to let him go but this year it was a sensible discussion.
"There's no doubt it's a huge loss. It's a challenge for us because it won't be the same without Ronaldo. He's the best player in this world of ours - by absolutely miles.
"He's streets ahead of Lionel Messi, streets ahead of Kaka. Look at his figures. They're unbelievable. The attempts he had on goal, the attacks in the penalty box, his positions, his headers, his shots."