The arrests made in the attack on Tottenham fans involve AS Roma fans.
So far the two hooligans arrested have been identified as Roma ultras rather than Lazio.
A bar in Campo dei Fiori called the Drunken Ship was targeted by a group of around 50 masked thugs wearing full motorcycle helmets to hide their identity, armed with knuckle-dusters, knives and iron bars.
At first it was believed these were Lazio ultras targeting the fans ahead of today's Europa League match, but details are emerging of a different reason.
The two figures arrested so far with the accusation of attempted murder have been identified as 26-year-old Francesco Ianari and 27-year-old Mauro Pinnelli, both of them Roma ultras.