A 53-year-old man has remained in a critical condition after he was attacked outside Anfield before Liverpool's Champions League semi-final against Roma.
Two men from Rome, aged 25 and 26, have been arrested on suspicion of attempted murder, Merseyside Police said.
The victim, thought to be a Liverpool fan from Ireland, has a head injury and is being treated in hospital.
In a statement, Liverpool FC said it was "shocked and appalled" and would be offering the victim "our full support".
The attack happened outside The Albert pub in Walton Breck Road before kick-off.
Detective Inspector Paul Speight said: "Witnesses report that the victim was hit with a belt and then fell to the ground.
"His condition is currently described as critical and his next of kin have been informed."
It is not known where on the island of Ireland the victim comes from.
About 80 Roma fans are thought to have used a side road to reach an area where Liverpool supporters had gathered.
One supporter was seen motionless on the road and BBC Sport footage showed another fan carrying a hammer.
BBC Sport news correspondent David Ornstein said the pre-match trouble started at 19:05 BST when a "group of Roma fans arrived via Venmore Street, burst on to Walton Breck Road and attacked, many using belts".
Liverpool fans claimed up to 20 Roma supporters armed with bats and belts charged and attacked outside The Albert.
Student Ryan Ellis, 22, said: "It was horrible to see, some had bats and others were swinging at people with belts with buckles out.
"They were beaten back by Liverpool fans and then the police on horseback charged."
One steward said: "I saw the badly injured fan on the ground. He seemed unconscious and paramedics put an oxygen mask over his face and took him to hospital."
Builder Mark Wilson, 39, said: "There were about 20 Roma fans who charged and were hitting out at people with belts.
"Liverpool fans then threw bottles and cans at them and chased them off."