No excuses. If Arsenal was at full strength, they would not be losing, regardless if United was at full strength. United fans think Arsenal is going to crumble in the league because of this defeat. It's the FA Cup, it is a seperate competition. Arsenal still has the upperhand where it counts.
Also to point out, United is at a full defense. This makes all of the difference in this game and you know it. Arsenal is using Traore, Toure, Hoyte, and Lehman. Toure has been out in Africa for a month, as was Eboue.