At least three football fans in Brazil have been taken to hospital following clashes between rival groups of fans at Vasco's key game against Atletico Paranaense.
Four-time champions Vasco were looking to avoid being relegated from the Brasileirao - however the game was abandoned for an hour after intervention was required to stop the fighting at the Arena Joinville, where the game was moved to following previous incidents of fan violence.
An early goal from Atletico Paranaense which put Vasco on the verge of relegation prompted the shocking violence, with television cameras showing images of fans being kicked and punched into unconsciousness.
Eventually order was restored and the game resumed, with Paranaense running out 5-1 winners to seal Vasco's fate.
Atletico director Luis Alberto, who was in tears as the brawl broke out in front of him, said he had never seen anything like it in his life.
"We are having a World Cup here next year. It's a shame that this kind of stuff still happens," he told TV Bandeirantes.
"We have to maintain our concentration right now, wait for the adrenaline rush to come down to try and come back to the match.
"I saw a fan being beaten until passed out. I've never seeing anything like this in my 20-year career."
According to reports there was no police presence inside the ground, with the security operation being taken care of by a private firm. There were officers outside the stadium however.
"A football match like this usually demands 80, 150 and 200 men working exclusively on it. Men that we could be using elsewhere, taking part on other operations and protecting the city," a police officer explained to Radio Globo after being questioned on why police were not inside the ground.
"These officers are taking care of other interest areas and we also have men on leave, because they have the right to take a day off and end up losing those days off because of the matches.
"The police force allocated to the match is going to work exclusively outside the stadium. Inside, only private security hired by the teams."
The draw for the 2014 World Cup, which takes place next summer, was made on Friday.
Watch the video, which contains scenes of extreme violence, above.