Liverpool supporters were attacked ahead of their Champions League clash against Napoli on Tuesday evening.
And one fan was left in hospital after he “collapsed at half-time due to significant blood loss after being ambushed in a bar”.
The injured fan, named Steven Allen, was visited in hospital by Liverpool’s chief executive Peter Moore.
Moore tweeted updated on Allen’s condition, writing: “He’s been seen and will be monitored throughout the night. He asked me to thank everyone for their concern.”
The attack was posted to a Facebook group for Liverpool fans by Allen’s friend Matty Johnson, who hadn’t travelled to Italy.
“My mate Steven Allen is currently in Ospedale Cardarelli hospital in Napoli,” Mr. Johnson wrote. “He collapsed at half-time due to significant blood loss sustained after being ambushed in a bar by Napoli fans.
“If anyone is in Naples or know of anyone in Naples and is not far from that hospital please could they visit the hospital and check on him.”
Moore was alerted to the matter and he visited Mr. Allen in hospital.
"We will not leave him until we are comfortable that he’s fine, so can everyone stop worrying for now,” he tweeted.
“Trying to get him seen by a doctor, but there’s a distinct lack of urgency here from the police and medical staff.”
He later added: “The hospital staff and the police have now helped Steven and been very cooperative. He’s been seen and will be monitored throughout the night.
“He asked me to thank everyone for their concern."
Merseyside Police reported that a group of men riding scooters attacked Liverpool supporters in the city, with.two Liverpool fans sustaining injuries.
“Two men from the UK, aged 26 and 46, sustained superficial cuts and grazes to the head and were treated at the scene before continuing to attend the match," a police statement read.
"Local police area aware and Merseyside Police are working with police colleagues in Naples to assist in the policing of the Champions League fixture tonight."
One Liverpool fan told the Liverpool Echo: "We were just trying to have a quiet drink before going to the apartment and had just paid our bar bill.
"Next minute we could see about 10 scooters flying down. They slowed right down and their faces were covered with scarves and helmets.
"Next second they are jumping off swinging belts towards us. Must have all happened in 90 seconds but some lad got hit by a belt.
"Twice I've had bother here now. I am never coming back."
Liverpool were beaten 2-0 by Napoli as the defence of their title got off to a disappointing start.