Arsenal have shrugged off the “cup team” tag for now, but not in the way they would have wanted. The holders will have to seek fulfilment elsewhere after a defeat that showed up the fragility of their reserves to an extent that should concern Mikel Arteta.
Southampton fully merited their win on the strength of a dominant first half and an effective late rearguard action; they will travel to Wolves in the fifth round and should feel confident of a strong run in this competition if they continue to treat it with the seriousness shown here.
