RSL will probably put their starters out there for 20ish minutes then you'll see kids from then on. I doubt ManU will follow the same pattern but maybe sprinkle the starters throughout. In the end this is a friendly and means nothing to either team. It is a spectacle of individual skills and I doubt you'll see much of a game plan for either team.
I wish I could attend but I will settle for catching it on ESPN 2 tonight instead.