Lazio says its players have received threatening phone calls from people demanding that they lose Sunday's Italian Cup final to Roma.
Lazio communications director Stefano De Martino made the revelation during the pre-match news conference Saturday, adding that police have been informed.
There were already serious concerns about of fan violence in the derby.
Several fans were stabbed and an ambulance was attacked before the teams' last meeting in April, which ended 1-1. Fans for both clubs have also come under attack this season for racist chanting.
Raising tensions even higher is the fact that this is the first time the teams have met in the Cup final.
The winner of the match at the Stadio Olimpico will qualify for the Europa League group phase.
