It's all about taking your chances against Arsenal, because when you are up against a team whom keep possession well, you are always going to have to make the most of all your chances throughout the course of the game.
Pressing is Key
Against a team like Arsenal, you NEED to pressurize the players, and to close them down, otherwise they will simply find space. I personally think that the difference between Barcelona and Arsenal is the work ethic.
Barcelona have incredible movement when on the ball, they simply create so much space for each other. Arsenal on the other hand, besides Walcott, they don't seem to have the pace moving forward. Look at it this way, even Xavi gets into the act when Barcelona attack.
Pressing would cause the players to panic a little, and potentially wrongly place/weigh the pass, hence Arsenal losing the ball.
And for Attacking
I think that against Arsenal, you have got to do it either one way or another, and the two methods of doing so is through either playing a game which includes a lot of crosses for your strikers to get on to or simply to outthink Arsenal, Koscielny sometimes, in my opinion is a bit too erratic in his tackles.
And personally, when I watch Arsenal play, I think that Koscielny gives away way too many penalties thanks to his tackles. So that's what you really have to do, to sort of sniff around the edge of the box and simply looking for an opening, because one will certainly open up.
