He told The Sun: "It would be a beautiful sensation. If I score against them, it would be spectacular.
"I can't say how I'd celebrate - it would be something spontaneous - but I'd love to be in that situation."
On his Old Trafford fans, he added: "I'm sure they will receive me well.
"After the years I spent there and the friendships I have, I'm sure it's one of the places where they'll applaud me most. It was a beautiful time."
Will Ronaldo break United hearts? Or will the emotion be too much for him? Give us your shout below...