Fans fought with riot police as the Athens derby between Panathinaikos and Olympiakos was called off after violence broke out.
Olympiakos striker Alfred Finnbogason was hit by a flare as he walked on the Apostolos Nikolaidis Stadium pitch with his team-mates.
Referee Andreas Pappas called off the Greek Superleague match 30 minutes after the scheduled kick-off.
After the decision was announced, fans invaded the pitch.
Broken chairs and advertising hoardings littered the field and missiles were launched at police.
The violence started outside the ground and over 50 people were arrested.
Olympiakos fans were not at the match as visiting supporters are banned in the Greek Superleague. Their side leads the table by eight points from Panathinaikos.
The fixture, known as 'the derby of the eternal enemies', has a history of violence between supporters.