I actually expect Rooney to be more of a difference maker this game than pretty much anyone else.
Talking about influencing the general flow of the game throughout it all.
Ronaldo and/or RvP might be the biggest goal threats, but United's and Real's play will have a lot to do with how Rooney plays.
I believe his job will be to do to Alonso what he did to Arteta against Arsenal, works out too since they play in the same/similar position, and Rooney doesn't have to sacrifice his positioning in order to do his job.
Ronaldo is Ronaldo and expecting him not to have a chance is ridiculous, but I think Rafael & whoever else is going to help out a bit will manage to keep him relatively quiet as long as Rooney does his job on Alonso. You keep Alonso at bay, stop the supply, and all of a sudden those chances become more sporadic.
However Real is incredibily dangerous on the counter and I just hope Evra doesn't go too high up the pitch and leave us open at the back too often.
God I'm just so pumped up about this already, I can't begin to imagine how it'll be like once the game starts....