Between 20 to 30 hooligans wearing motorcycle helmets and totting clubs and crowbars invaded the pitch of a UEFA Youth League match on Tuesday afternoon between Olympiacos Piraeus and Bayern Munich in an attempt to reach a portion of the stands where German fans were sitting.
The unprecedented incident took place at Olympiacos' training facility in the Rendi district, southwest of downtown Athens, along a busy highway.
The hooligans threw flares into the stands, while four people were injured.
The game was interrupted in the 84th minute, with the German teens ahead 0-4. Players from both sides immediately fled towards the locker rooms, with Olympiacos players later emerging to head towards the German fans to apologize for the violence.