I think Diaby is going to have a big game. If he sits just in behind Bendtner United are crap at picking that kind of player up, particularly if our full backs are feeling like getting up the pitch. and with Denilson/Fabregas' abilities to pick a pass, I can absolutely see him scoring.
In theory this should be a high scoring affair actually, given the defensive injuries of Arsenal. I hope there's a good ref that isn't card happy, or else it could well turn into a bad-tempered card-fest. United could really, really use Hargreaves and Scholes for this one.