Sunday's Inter-Lazio clash in Serie A was postponed after the tragic death of a Lazio supporter during clashes with the police. All other games kicked off 10 minutes late to pay respect for the victim, but trouble in Bergamo resulted in the abandonment of Atalanta-Milan after just seven minutes.
Local authorities said there had been a "tragic error" when police intervened to quell violence between fans of Lazio and Juventus at around 9am local time. The victim, a Lazio fan, was shot during the clash at a motorway service station in Badia al Pino near the Tuscan city of Arezzo.
The Lazio fans were travelling to a match against Inter in Milan, but that game was postponed following urgent talks between the Lega Calcio and the Italian government. The Juventus fans were reportedly on their way from Naples to an away match against Parma.
"It was a tragic error," said Arezzo police chief Vincenzo Giacobbe. "Our agent had intervened to prevent the brawl between these two groups, who had not been identified as fans," Mr Giacobbe said, according to the news agency ANSA.
Other games started 10 minutes late with players and officials wearing black armbands.
The victim was identified as Gabriele Sandri, a 26-year-old disc jockey from Rome. He was also well known to members of the Lazio squad and staff.
As the Stadio Giuseppe Meazza in Milan was emptied, Lazio staff members were seen walking away in tears after discovering the name of Mr Sandri.
The fan was apparently shot while in a car outside the motorway restaurant. Earlier reports said the fan had been killed during the brawl. An investigation is under way.
Prime Minister Romano Prodi said he had been informed of the incident and told reporters: "Certainly these events are very worrying."
News of the death prompted anger among Italian fans around the country. In Bergamo, where Atalanta were playing Milan, police and fans clashed ahead of the match. The game was abandoned seven minutes after kick-off, when fans tried to smash down a barrier and force their way onto the Stadio Azzurri d'Italia pitch.
Italy is battling against a serious hooligan problem and suspended all football for a period in February when a police officer was killed in riots outside a Sicilian derby match in Catania.
Sporadic violence has continued in recent months despite the security crackdown prompted by February's incident. Officials said last month that fan injuries caused by violence around stadiums had been cut by 80 percent from last season but that it was difficult to combat violence away from the grounds.
[LAZIO FAN KILLED] - [MATCHES POSTPONED] - [PROTESTS]