The pitch, goals and coaching areas at the Panionios Athens ground have been badly damaged in what is believed to be a protest at a decision to use the venue for a Europa League game by city rivals AEK, dpa reported.
Around 80 masked intruders entered the ground in the Nea Smyrni district of Athens, dug up the pitch and destroyed club property, Greek reports said Tuesday.
Pitch problems had forced AEK Athens to move Thursday's second leg of their Europa League play-off tie against Dundee United from their Olympic Stadium to the smaller Panionios ground, a decision which had sparked protests from Panionios fans.
AEK lead 1-0 after the first leg of the qualifying play-off.