A Napoli fan was taken to hospital with facial injuries after being assaulted following the Italian side’s defeat by Liverpool at Anfield on Tuesday.
Police received reports that a 26-year-old man, believed to be a Napoli fan from Essex, was assaulted.
Liverpool won 1-0 to progress to the Champions League knockout stages.
While inquiries into the incident are ongoing, the police are looking for anyone with information on what exactly happened to the fan.
In April, Liverpool fan Sean Cox was left in a coma after being attacked outside Anfield before the Champions League semi-final against Roma.