We have to play Valencia in these games, he can really help out either Rafael or Smalling against Ronaldo. In games against Chelsea/City this season he has been great at helping out the right back and at the same time get up there and help out the attack. Young will probably be given a similar task on the left aswell, Rooney in midfield/just behind RVP.
If Fergie gets the tactics right then this is no foregone conclusion, in some ways Real being the favourites is good for United. The home leg advantage is also a help as I return leg in Madrid would be so difficult.