Athens: Greek Super League referees announced on Monday they were bringing forward their strike action by a week to January 4-5 in protest at the latest assault on one of their number.
Hooligans armed with firecrackers attacked the home of one of the match officials in charge of the Volos-Olympiakos scoreless draw on Sunday.
The Greek football federation strongly condemned "the new, mafia-type attack on a Super League referee".
Olympiakos protested about "bad officiating" and filed a lawsuit against the five referees, charging them with bribery.
The Piraeus club have also sent protest letters to football governing bodies UEFA and FIFA, claiming "a deliberate and surgically precise alteration of the outcome of a match in which VAR was used".
The Greek federation has suspended the five officials pending the outcome of their investigation.
"The implementation of the VAR system in the match was undoubtedly below expectations," the federation said.
The referees association had called their strike initially for January 11-12 to protest at a "lack of respect" for their job.
They complained of bullying, negative comments from club representatives which remain unpunished and lawsuits against them for their decisions on the pitch.
"The non-protection of referees and Greek football in general from comments, announcements and verbal violence made daily by club administrators, journalists and many others involved in the sport have left us no other choice but to take action," the referees said this month.
They said they will officiate the next round of matches on December 21-23 before beginning their indefinite strike.
Olympiakos are in second place in the table after 16 matches with 38 points, two behind leaders PAOK Thessaloniki.