Tear gas, stun grenades and knuckle-dusters provided a grim, bloody backdrop as hooliganism returned to haunt Europe's top leagues this weekend.
From London's showpiece Wembley Stadium to Munich's glittering Allianz Arena and at the 2004 Olympic Stadium in Athens, fans fought hit-and-run battles with riot police.
Fourteen fans were arrested and four police officers were hurt after Millwall fans fought amongst themselves as their team went down to a 2-0 defeat to Wigan in the FA Cup semi-finals at Wembley.
Police wielding batons eventually brought the disorder under control.
"Our position is clear. Anyone associated with our club found guilty of violent behaviour will be banned indefinitely from Millwall matches in addition to any punishment they receive from the authorities," said Millwall chief executive Andy Ambler.
South London club Millwall had been plagued by hardcore violence during the dark days of the 1970s and 1980s.
Saturday's fighting was witnessed by millions of people worldwide tuning into TV coverage of the sport's oldest cup competition.
Wigan chairman Dave Whelan said he had been stunned by the violence which left some fans injured and children in tears.
"I can't understand why the Millwall fans would fight each other," said Whelan.
"I understand if they want to fall out with the visiting team, but why would they fall out amongst themselves? It just gives football a very, very poor reputation."
In Munich, police warned of a "new dimension of violence" after 16 officers were injured and more than 60 supporters detained before champions Bayern Munich's match against Nuremburg.
"We are shocked and disappointed about what happened before the Nuremberg game," Bayern chairman Karl-Heinz Rummenigge told Munich newspaper AZ after the clashes between rival 'ultra' fans.
"There is no excuse for the behaviour of these ultra fans."
According to reports, a group of 400 Nuremberg fans was attacked by 120 Bayern fans en route to the stadium before the away fans then turned on police, using stones and bottles.
In all, 61 fans were detained -- 31 from Munich and 30 Nuremberg supporters -- and questioned over offences ranging from assault and resisting arrest to breach of the peace.
Weapons, including knuckle-dusters, were used in the fighting.
Two key matches in the Greek Super League saw hundreds of supporters clash with police who resorted to tear gas and stun grenades to quell the assault.
The most serious incidents happened at the Athens Olympic Stadium where the match between the home team AEK and Panthrakikos was suspended.
The game was halted when hundreds of angry AEK fans dashed onto the pitch after the visitors took a 1-0 lead courtesy of an own-goal in the 87th minute.
As the stadium emptied, some 300 fans remained, destroying plastic seats.
Going into the match, AEK had won just one of their last seven games and are in danger of being relegated for the first time in their history.
An hour-and-a-half before the start of that game, Olympiakos fans, Panathinaikos supporters and police clashed outside Karaiskaki Stadium.
Fire bombs and rocks were thrown at police who responded with the use of tear gas and stun grenades.
Back in the English Premier League, Newcastle fans fought running battles with mounted police.
Twenty seven fans were arrested and at least three police officers injured following Newcastle's 3-0 home defeat to bitter local rivals Sunderland.
Police said they were pelted with missiles as they clashed with home fans attempting to confront Sunderland supporters at the city's railway station.