Milan and inter had tougher groups than Arsenal and United though.
Inter's wasn't hard either, but looking at Inter's squad and their form, it was surprising to see them win the group so comfortably.
P.S: And Arsenal had a much tougher group than Inter or Milan. Dortmund and Marseille are big names, so Arsenal had to be better than at least one of them while Milan only had to be better than Plzen and BATE.
