Two key matches in the Greek Super League on Sunday saw hundreds supporters clash with police who resorted to tear gas and stun grenades to quell the violence.
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.
Panthrakikos and AEK players quickly left the pitch as they were being chased by the hooligans.
As the stadium emptied, some 300 fans remianed, destroying plastic seats.
Riot-trained police used tear gas to chase the troublemakers from the pitch.
Panthrakikos and AEK officials tried to convince referee Stavros Tritsonis for more than an hour to restart the match but his final decision to suspend the game may lead to AEK's relegation and heavy fines.
The match before some 30,000 spectators was a key one as the two clubs near the bottom of the Super League battled to avoid being demoted.
Going into the match, AEK had won just one of their last seven games and were 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.
That match ended 1-1 with Panathinaikos needing to win to qualify for a post-season playoff for the Europa League while Olympiakos had already clinched the Super League title last month.
Fire bombs and rocks were thrown at police who responded with the use of tear gas and stun grenades.
There were no reports of arrests but during the violence a sports reporter for Skai television was beaten by a group of fans. He was taken to the hospital for treatment of broken ribs.
"Our colleague Giorgos Tselikas from the television station Skai was attacked by hooligans outside Karaiskaki Stadium because he is a journalist. It is yet another unfortunate incident which has been added to a long list of violent attacks against journalists during football matches," president of the Athens journalist union Dimitris Trimis said in a statement.
Journalists held a short work stoppage at all Super League matches during Sunday's matches to protest the violence against colleagues.