It's a silly question really because we shouldn't have a defined XI, it should be using our squad to nullify our opponents threats and also to expose their weaknesses.
SCUM - Their weakness is their full backs, AJ spit roasted Evra in the Semi Final last year and I think Rafael's positional sense is awful. If you can work situations to get Vidic 1-1 then he's useless. Equally you have to stop Nani, Valencia or Young, whoever plays wide need to be pushed back by Richards and Clichy, if you let them dominate possession they'll destroy you.
CHELSEA - Unknown quantity so far with Boas as manager.
ARSENAL - Their weakness is their strength and physical stature, we should be competing for every ball and being as aggressive as possible without going too far. Set pieces we should destroy them. Defensively you have to stay compact and not let the neat passes inbetween defenders, concentration is the key.