What was supposed to be an audience party and a hot derby between arch-rivals Gremio and Internacional in Porto Alegre in southern Brazil ended with chaos scenes - before the match even had time to begin.
It was before the match that a group of Internacional supporters threw stones at Gremio's bus.
On the club's social media, pictures have been posted on player buses where you can see how one of the windows has broken.
Two suspects have been arrested
Gremio's Paraguayan football player Mathias Villasantifick was taken to hospital by ambulance.
"After the cowardly and absurd aggression suffered by our delegation, Harvi told the Gaucha Football Federation (Gaúcha Football Association) about our decision not to play the derby today," Gremio wrote on social media.
Internacional also went out on social media and denied the violence and told that two suspects had been arrested.
Later in the evening, information came that Mathias Villasanti had been treated for concussion and head trauma, had cuts on his face and had to spend the night in hospital for further observation.
It is still unclear when the match will be played.