First of all, this is dependant on Fabregas' fitness. If he doesn't play we will have to re-evaluate this play.
I've watched Arsenal a lot over the last years and the concept the other PL top teams use against them is to let Arsenal play up to their penalty area, and then break with purpose. Man United and Chelsea have both stung Arsenal badly in games where they have had less possession.
Here is the problem: Barcelona won't do this. It is in their genes to play a possession game of their own.
Add to that that Arsenal will NEED to win to have the slightest of chances at the Camp Nou, and that Barcelona seemed very content with drawing away to Stuttgart and you have a great play.