Among the walking wounded are Laurent Koscielny (calf), Nacho Monreal (foot), and Calum Chambers (the FA). Mikel Arteta is also unavailable (calf) so the back five -- whoever they are -- won't have his protection, either. It's likely that three fullbacks will be playing in different capacities, likely with Mathieu Debuchy playing centrally and Hector Bellerin on the right side. Debuchy is relatively good in the air, and he's experienced. Hopefully that will help him not be terrible at this.
Theo Walcott and Aaron Ramsey are in differing levels of un-fitness as well. Ramsey may be fine, but acccording to Wenger he'll have exams on his hamstring today and tomorrow, "so we'll see." Hopefully it's just tired from kicking the shit out of the ball and he'll be good to go. Theo is still recovering from the groin injury, and has been in training for a couple of days but "lacks competition and fitness to come back to a good level." So he won't be around to do things like this on Saturday.
News of a Jack Wilshere setback was also debunked, with Wenger saying basically that he's too hurt to even have a setback yet, so everyone pipe down.