Three Middlesbrough fans have been stabbed during violence ahead of the club’s Uefa Cup tie in Rome.
Police said the attack came from an “organised gang of Italian thugs” who attacked two bars where the English fans were drinking.
In all 13 fans were hurt, although none of the injuries is thought to be serious.
A 39-year-old man underwent surgery in Rome overnight and he remains in hospital for observation. An 18-year-old was also treated in hospital and was expected to be released on Wednesday.
Italian Police with batons were broke up the violence.
A spokesman for Cleveland Police said a lighted flare was thrown into a bar where Middlesbrough fans were drinking.
Middlesbrough chief executive Keith Lamb confirmed there had been violent clashes between supporters.
“There was an incident in one of the bars in a square in Rome,” Lamb told Radio Five Live.
“Some Boro fans were drinking in a bar and the bar was attacked by some Roma fans.
“A number of Boro fans have been injured – a small number – and taken to hospital and received medical treatment.
“As far as I’m aware everybody is okay now, although one was retained in hospital but is in a stable condition.”
Cleveland Police appealed for calm in the run up to the second leg of the cup tie, in which Boro lead 1-0.
Last year a Middlesbrough fan died after being stabbed outside a bar in Amsterdam, after travelling to watch his team in the Uefa Cup.