Gonzalo Higuain is in disbelief that Napoli were eliminated from the Champions League despite a strong record.
Here are the five teams Manchester United could face in the Champions League knockout phase.
Arsenal fell to Napoli by a matching scoreline to their prior victory over the Partenopei at the Emirates, but secured qualification to the knockout stages nonetheless.
Chelsea striker Demba Ba scored the winner against Steaua Bucharest which ensured Mourinho's men earned top spot.
Arsenal manager Arsene Wenger believes the dismissal to Arteta was a stringent punishment.
The eldest player in the Arsenal squad at 33, Tomas Rosicky was picked from the start in their crucial Champions League game.
Chelsea finished top of their group, and will now hope to reap the rewards in the Champions League knockout phase.
Arsenal are through after a 2-0 loss to Napoli.
Defensive rock Per Mertesacker was dejected at full-time due to the defeat to Napoli despite seeing Arsenal progress into Champions League knockout stage.
Leandro Damiao looks set to join Santos in January after a deal was struck between Internacional and a third party.