Update 5.11pm: The family an Irish Liverpool supporter left fighting for his life after being attacked before last night's Champions League match have flown from Dunboyne, Co Meath to maintain a bedside vigil.
Sean Cox, a 53-year-old father of three, suffered serious head injuries after being assaulted outside Anfield stadium yesterday and remains in a critical condition at Walton Neurological Centre.
Two men in their 20s from Rome have been arrested on suspicion of attempted murder.
Sean is a popular and well-respected businessman, friends have said.
Damien O'Reilly, a friend and local councillor, described Mr Cox as a role model and cornerstone of the community.
He said: "He has done huge work locally. Sean is heavily involved in the community and the local GAA club.
"Everyone is just in shock and we are praying for a speedy recovery."
Other pals and fellow football fans have taken to social media to express their disgust at the attack, to wish Mr Cox well and a GoFundMe page has been set up to help with medical bills and other costs.
Update - 2.39pm: Journalist recalls 'sudden attack' on Meath man outside Anfield pub
Sunday Times football correspondent, Jonathan Northcroft, has described what he saw last night outside Anfield where an Irish man was left in a critical condition after being attacked.
Northcroft told RTÉ Radio One's Sean O’Rourke show that he saw a group of Italian fans as he walked towards the press entrance at Anfield.
He said: "It's one of those - it doesn't quite look right. Anyone that's been to Anfield will know there's quite a well-known pub called 'The Albert' just on the corner there.
"So I was walking just past 'The Albert' into the ground through the gates. And I could see out of the corner of my eye really - there was a group of Italian lads who were just sort of coming down Venmore St, which comes onto Walton Breck Road, which runs behind Anfield.
"I looked back around and these Italian guys ran into the middle of the road. They started shouting and chanting at any Liverpool fans that were nearby. They seemed to want to make a big show of doing something right in front of The Kop."
He then described what happened next.
He said: "A couple of guys shouted back and that was enough for an attack. And they had belts in their hands - moved in on the Liverpool fans who'd been outside 'The Albert'.
"And picking on a couple of soft targets...the poor fella that was attacked was just one of a couple of older Liverpool fans outside 'The Albert' - it's quite a sedate pub really."
Northcroft said he noticed that there was little police presence in that particular part of Anfield.
He said: "I immediately knew there was going to be an easy target there. It was over so quickly as well. That's the thing that struck me. It was over so quickly.
"There was a lot of police in the area but they weren't on the scene at all, because by the time anyone reacted - these Roma fans were sort of running off - and the guy was left in the middle of the road."
"He was part of the group of fans outside ‘The Albert’. So he was just the nearest one to them, unfortunately for him.
He went on to say that Mr Cox was in the wrong place at the wrong time.
Mr Northcroft said: "I guess there were two or three of them - there was a bit of a scuffle. But he was the one that bore the brunt, it looked to me like they wanted to make a quick attack and get out of there. And as I say they picked a soft target.
"You could see that and I was about 20 yards away. And I went back into the middle of the road to see what was happening.
"And he was absolutely out. Lots of people around him were very concerned. And then the police did get round, which was a couple of minutes later. You could see the concern that they had as well and [they] sort of cordoned him off and waited for the ambulance to come."
Update - 12.59pm: A 53-year-old Irish man who is in a critical condition after an assault ahead of Liverpool's Champions League semi-final against Roma last night has been named.
He has been named as Sean Cox from Co. Meath, and he is being treated at Walton Neurological Centre.
He is a member of St Peter’s GAA club in Dunboyne, and the club released a statement saying: "The Club is aware of an incident involving our Club colleague, Sean Cox, at the Champions League game in Anfield last night.
"Sean is a long serving and popular member of St Peter's GAA Club in Dunboyne. At this point we hope that Sean is receiving all of the medical care he requires and that he makes a full and speedy recovery.
"Our thoughts and prayers are with Sean and his family, and we hope that they get the privacy and space they need. We will not be making any further statement at this time."
6.38am: Police arrest two Italians as Irish man fights for his life after attack outside Anfield
Two men from Rome have been arrested on suspicion of attempted murder after a Liverpool supporter was left fighting for his life following an altercation between fans ahead of the Champions League semi-final at Anfield.
The 53-year-old man, reported to be from Co. Meath, is being treated for his injuries at Walton Neurological Centre.
The man was believed to have been with his brother and his condition is described as critical, Merseyside Police said.
The 25-year-old and 26-year-old were arrested after police launched an operation to track down the man's assailants amid scenes of violent disorder ahead of Liverpool's clash with Roma.
Liverpool Football Club said it was "shocked and appalled" by the incident and urged fans and those who attended the game to help Merseyside Police with their appeal for information.
Pre-match trouble outside Anfield started when group of Roma fans arrived via Venmore St, burst on to Walton Breck Rd & attacked, many using belts. #LFC fan knocked to floor & received lengthy medical treatment. Skirmishes, projectiles, at least 1 hammer in hand, police arrived pic.twitter.com/Yaby4q5f0Y— David Ornstein (@David_Ornstein) April 24, 2018
Detective Inspector Paul Speight, said: "We believe the victim was in Liverpool with his brother for the Liverpool v Roma semi-final and was assaulted during an altercation between Roma and Liverpool fans near to the Albert pub at about 7.35pm.
"Witnesses report that the victim was hit with a belt and then fell to the ground.
"Paramedics treated him at the scene and he was taken by ambulance to Walton Neurological Centre, where he is being treated for a head injury. His condition is currently described as critical and his next of kin have been informed."
The Liverpool fan's alleged assailants were among a total of nine men, aged between 20 and 43, who were arrested for various offences before and after the match.
The offences included affray, assault, possession of offensive weapons, possession of a controlled drug, criminal damage and being drunk and disorderly.
Detectives are also investigating the use of flares outside the ground, the force said.
Merseyside Police Chief Superintendent Dave Charnock, said "a number of those in the crowd that had gathered to greet the Liverpool team coach were in possession of flares and work is ongoing to identify those responsible".
He added: "The vast majority of the 52,500 fans attending the game were well behaved and went to watch a good game of football.
"However, a minority of fans from both Liverpool and Roma were involved in isolated pockets of disorder in the city centre and near to the ground."
Anyone with information or mobile phone footage of the disorder was urged to contact police.
Mr Charnock said: "We will be reviewing CCTV footage, our own body worn camera footage and working with the club to identify those involved in any of these incidents so we can put them before the courts.
"And I would appeal to anyone who has any information, or mobile phone footage, in relation to any of these incidents to contact us.
"Finally, I would like to thank the Liverpool Football Club stewards and the police officers who were out on the ground tonight for their hard work and professionalism throughout the evening."
In a statement, Liverpool FC said: "(We are) shocked and appalled after a Liverpool supporter was left in a critical condition having been attacked prior to the Champions League fixture against AS Roma.
"Our thoughts, in the first instance, are with the victim and his family at this very traumatic time. We will be offering them our full support.
"The club has been liaising with the emergency services since the incident occurred and will continue to do so.
"Liverpool FC directs supporters and those in attendance at the game to Merseyside Police's appeal for information."
UEFA condemned the attack: "UEFA is deeply shocked by the vile attack that occurred ahead of the Liverpool FC v AS Roma match and our thoughts are with the victim and his family.
"The perpetrators of this ignominious attack have no place in and around football and we trust they will be dealt with utmost severity by the authorities.
"UEFA is waiting to receive full reports before deciding on potential disciplinary charges."
Roma also condemned the "abhorrent behaviour" of a small number of their supporters.
"AS Roma condemns in the strongest possible terms the abhorrent behaviour of a small minority of travelling fans who brought shame on the club and the vast majority of Roma's well-behaved supporters at Anfield after getting involved in clashes with Liverpool supporters before last night's fixture.
"There is no place for this type of vile behavior in football and the club is now co-operating with Liverpool Football Club, UEFA and the authorities.
"The club's thoughts and prayers are with the 53-year-old Liverpool fan in hospital and his family at this time."
Anyone with information can also contact Merseyside Police via Twitter @MerPolCC or Facebook Merseyside Police CC.
They can also call 101 or contact the independent charity Crimestoppers anonymously, on 0800 555 111 or via an online form at crimestoppers-uk.org/give-information/give-information-online/