Gabriele Sandri, a 26-year-old disc-jockey, was shot by a police officer after Lazio and Juventus fans clashed at a gas station on the A-1 freeway near the town of Arezzo. As news of Sandri's death spread across Italy, riots involving soccer fans broke out across Italy.
Players at AC Milan's game against Atalanta in Bergamo walked off the field after 40 minutes because of fear for their safety. Fans were battling riot police and threatened to storm the field.
League leader Inter Milan's match with Lazio was postponed on Sunday as was Roma's home game with Cagliari.
Roma general manager Rosella Sensi said her team's game was postponed out of solidarity with its Roman rival, rather that fear of more violence.
"In a sign of solidarity with Lazio fans and all the city of Rome grieving the death of Gabriele Sandri," she said, "it is right to ask the postponement of the game this evening in the Stadio Olimpico against Cagliari."
At other games across Italy, fans took down banners to show respect.
Violence has been a huge problem in Italian soccer.
A policemen was killed in riots outside Catania's match with Palermo in Sicily earlier this year, and league play was suspended. Authorities have since instituted new security rules at stadiums across Italy.