A Djurgarden fan has died following an assault that occurred ahead of the club's Allsvenskan fixture at Helsingborg on Sunday.
The incident happened on the opening weekend of the season at Olympia, with the Swedish FA confirming the victim to be a 43-year-old Stockholm man.
Police are yet to make any arrests, but the match was abandoned at the end of the first half with the scores at 1-1 after news of the man's death spread among the travelling supporters.
Tensions between supporters of the two clubs threatened to boil over when some of those in the away end began to make their way onto the field of play.
"It is a black day," said Helsingborg sporting director Jesper Jansson. "It is extremely tragic for this guy's family, for football and for the whole community really."
The incident follows clashes in Helsingborg on Saturday that reportedly saw five people taken to hospital.