I feel the return of Abidal is a plus for Barca they've got Milito and Marquez to cover in the centre of defence. Arsenal's central defensive pair looks more suspect with Vermaelen (some part to blame in last weeks goals) and Sol Campbell (who's got his walking stick out today according to reports). Bojan scored 2 at the weekend, he might be up for starting but I'd say it's going to be Messi up top, Henry left, Pedro right, the midfield trio does not matter, they are all great at retaining posession.