Rome police confirmed today that 50 armed hooligans stormed the Drunken Ship pub at 1am before embarking on a brutal attack that left several people injured.
Italian sources said Spurs fan Ashley Mills, born in 1987 and believed to have been stabbed, was seriously injured and was being treated at the city's San Camillo Hospital.
The hooligans rushed the bar armed with knuckle dusters, baseball bats and broken bottles in an attack described as "obviously planned" by officials.
Tottenham fans had been signing and drinking in the Campo de Fiori venue ahead of tonight's Europa League game.
Lazio's notorious 'Ultras' fanbase have been blamed for the attack, however, club president Claudio Lotito tonight denied such allegations, claiming instead "foreigners" were to blame.
"Lazio fans had nothing to do with what happened last night in Campo de Fiori," he said.
"When it emerges who was really responsible, some people will be surprised. It is all too easy to speak about aggression from people whose faces are covered and say that they are Lazio fans.
"This isn't the case. Do you know, for example, that among these criminals, who must be punished in a harsh manner, there were also three foreigners (ie non-Italians)? I maintain that Lazio fans had nothing to do with it."
This evening, a spokeswoman from Rome police confirmed that Mr Mills was "not in danger of death" and would be kept in hospital for observation.
Other injured fans were named as Dave Lesley, Stephen Tierney and Christopher Allen with Tottenham claiming the local police had told them nine fans had been hurt.
"The person who was most seriously injured is not in danger of death and is resting in hospital until tomorrow. He suffered injuries to his skull and thigh," a spokeswoman said.
Rome police also confirmed that one person had been arrested near the scene of the attacks, without revealing that individual's identity or whether they had been involved in the violence.
The spokeswoman added: "One person was arrested last night and brought in for interview, having been found in possession of drugs in the vicinity of the Campo dei Fiori."
The pub landlord described the moment when the Spurs fans - who were "well behaved" and "drinking and singing quietly" - were attacked.
Marco Manzi said: "The bar was full of about 30 English supporters at 1am. Most of them were aged between 40 and 50 and they were well-behaved.
"Then arrived what I presume were Italian supporters wearing scooter helmets with their faces covered with scarves carrying stones and rocks. They arrived in the pub and they attacked the English supporters.
"Some of the English supporters tried to escape down Via dei Cappellari and it was in this street where one of them was hit by a knife.
"I think he was quite badly hurt but I don't know any more about him.
"The whole operation from start to finish was over in around 10 minutes. Most of the fans left and the police arrived."
Lifelong Spurs fan Colin McAteer, 59, from Harlow, Essex, said he was worried about the atmosphere surrounding the match, which officials said will have added security.
"It's devastating when people get hurt and stabbed. It makes no sense," he said.
"I am here on a walking stick because of the trouble we had when we were out in Slovenia (when Spurs played in Maribor) ... someone could die from this.
"It's no good. There is no need for that. For what? Bravado? There's no need. You can't hate anybody that much that you want to stab them up. It was quite a surprise."
He added: "We have heard stories that we are going to get picked off when we cross the bridge to the stadium...It's a bad time here."