Olympiacos' UEFA Youth League clash with Bayern Munich was suspended on Tuesday by a group of home ultras armed with bats.
Four fans were injured as the game was halted in the 84th minute when the Olympiacos ultras launched flares and sticks from the stands onto the pitch.
In horrifying scenes the hooded figures stormed the pitch and attacked defenceless opposition supporters in a brutal bid to get the game called off.
The referee called an immediate stop to the game with the German visitors 4-0 up.
But they weren't to be perturbed in their effort to finish the match.
When told to resume the match they instead whiled away the final few minutes by setting up a form of rondo in the centre circle.
Olympiacos are facing the possibility of a penalty or fine for the indiscretions of their supporters.
The two sides face eachother later on Tuesday in the Champions League group stage.
