Di Maria has taken Ronaldo's old No7 shirt at United.
"I wish the best to him, he deserves it, he's a fantastic player, he's going to do well at Manchester United," said Ronaldo. "And I said to him 'Number seven is a big responsibility' but I think he will be able to take that shirt because he's a fantastic player.
"Good for him. United is one of the best clubs in the world, and it's going to be good for him and I wish the best of luck to him.
"Personally, it's a shame for me because I liked Di Maria, a very important player for us as was Xabi Alonso (who is understood to be on the verge of joining Bayern Munich). They are situations that happen in football, players come and players go.
"They are decisions of the club. We have bought very well with players like James [Rodriguez], [Keylor] Navas and [Toni] Kroos and for that reason we are in good condition with a great squad."
For the big stories and the banter follow us on Twitter: @tribalfootball