Panathinaikos' match at home to Olympiakos was abandoned on Sunday after their fans attacked players on the visiting team's bench during the Greek Super League match and clashed with police outside the OAKA Stadium.
About four minutes after kick-off in the Athens derby, Panathinaikos fans invaded the area surrounding the pitch and attacked Olympiakos players on the team's bench. The match was stopped for about eight minutes before resuming.
Violence erupted again outside the stadium after Olympiakos scored the only goal of the match through Miguel Angel Guerrero in the 53rd minute. Police used tear gas to disperse Panathinaikos fans, TV images showed.
Tear gas wafted onto the pitch, affecting players and fans. German referee Marco Fritz abandoned the match in the 70th minute.
Olympiakos were awarded the victory, while Panathinaikos face a possible points deduction and a fine.
With the three points from Sunday's game, second-placed Olympiakos have 60 points, seven adrift of league leaders PAOK, while Panathinaikos are seventh on 32 points.
Greek football has suffered with violence off the pitch in recent years.
Last season, the top flight was suspended after PAOK Salonika president Ivan Savvidis entered the pitch with a gun in a hip holster.