2. Jeremy Mathieu vs. Olivier Giroud
Gerard Pique picked up a booking which means he would miss the Champions League tie at the Nou Camp. This means that another Frenchman comes in defence for Barcelona and to be honest, Mathieu is not the best player in that Barcelona side.
Defending against a fired up Olivier Giroud is not the easiest thing in the world and the French striker will have a point to prove against the La Liga side. If Giroud can bully the Barcelona defence, he could well get an early goal that gives Arsenal the confidence of getting another goal or two, after all, anything is possible in football.