One Inter fan was killed, and four Napoli fans were stabbed before the teams' Boxing Day clash at San Siro, while racist chanting was heard throughout the encounter.
The 35-year-old Inter fan, who has not yet been named, was hit by a van and rushed to hospital, but later died from his injuries, as reported by Sky Sports. And, in an unrelated incident, four Gli Azzurri supporters were stabbed about an hour before kick off in Milan, during violent clashes between the two sides' ultras.
One of these fans required hospital treatment for a wound to his abdomen, and two Nerazzurri ultras have been arrested in connection with the crime in the hours since.
The game itself was plagued with indignity and hostility as well, and Napoli manager Carlo Ancelotti revealed he had repeatedly attempted to have the game suspended following the incendiary and racist chants used in the terraces throughout the game.
Most of this chanting, which included monkey noises, was directed at centre back Kalidou Koulibaly, and the 59-year-old revealed the Senegalese defender was understandably affected, saying: "There was an abnormal atmosphere, we asked for the suspension of the match and three times they made an announcement over the PA.
"The player's (Koulibaly) nerves were shaken, he was nervous. Koulibaly is always well behaved and a professional, and doesn't often let himself go. But the chanting went on for the entire match.
"We asked three times to do something but it just went on. The solution? The match can be stopped but they need to have an idea when.
"After four announcements? Three? Four? The players were agitated, nervous. And this is not good for Italian football. And playing with a mentality that isn't calm, it's inevitable."
But the game continued, and ultimately Inter prevailed 1-0 thanks to Lautaro Martinez's 91st minute score, with the away side finishing with nine men following red cards to Koulibaly and Lorenzo Insigne.