A British tourist attending Saturday's Lazio-Roma derby was slashed across the buttocks in the classic Ultras calling card.
Allan Brown, 31, was visiting the city for the Easter break and took advantage of the game being on to visit the Olympic Stadium - venue for next month's Champions League final.
Mr Brown suffered wounds to the buttocks after being slashed by around ten
knife wielding Roma fans and was rescued by a passing Italian TV personality.
Buttocks slashing ia a trademark of Roma's notorious Ultras and the wound is not lethal but extremly painful and embarassing.
It was the latest in a series of incidents that have marred matches involving Roma's hardcore Ultra fans and will again raise questions about the suitability and safety of the venue.
Four British teams are left in the Champions League - which resumes next week - and this season Arsenal fans who attended last month's quarter final against Roma were also targeted.
In 2007 Manchester United fans during a Champions League quarter final were also attacked and the previous year Middlesbrough fans were set upon in the city centre.
UEFA have already said they are happy with security at the Olympic Stadium and are not willing to move the showpiece final which takes place on 27 May.
Police said Mr Brown was attacked as he drank a beer in the Ponte Milvio area, a few minutes walk from the stadium, at the end of the match but it is not known if he was on his own.
The group ran off after Italian TV star Paolo Calabresi, who presents a satirical show called Le Iene (The Hyenas) ran towards the group with his camera crew and shouted at them.
Signore Calabresi said: 'It all happened very quickly. I think he was on his own but I'm not sure. I saw that he was being attacked and kicked by a group of ten people.
'We ran at them and they ran off - two of them I saw get into a car. We picked him up off the floor and he said he was English and I saw that he was losing a lot of blood.
'It was really frightening. Then an ambulance crew arrived and took him to hospital. I hope he is OK.'
A spokesman at the Gemelli Hospital in Rome where Mr Brown was taken said: 'Mr Brown had wounds to his buttocks and had lost a lot of blood but his condition is not life threatening. Privacy laws forbid me from saying anything else.'
A Rome police spokesman said they could not rule out the possibility Mr Brown was targeted because he was English.
He added that police made five arrests during the bad tempered match which ended in a 4-2 win for Lazio.
Before the game police also seized a variety of weapons including knives, axes and smoke flares hidden by a bridge close to the Olympic Stadium.