Melbourne Victory won a record fourth A-League Grand Final, but their 1-0 win over Newcastle Jets was overshadowed by a VAR controversy.
Football Federation Australia (FFA) admitted hours after the decider had finished at McDonald Jones Stadium that Kosta Barbarouses' winning goal should not have stood.
FFA released a statement saying a "technical failure in the VAR system meant the Video Assistant Referee did not have access to the camera views which would have enabled him to make an offside ruling in the ninth minute goal scored for Melbourne Victory by Kosta Barbarouses".
Replays showed at least two players were offside in the lead-up to the goal, but the VAR gave the goal the green light.
Barbarouses' strike was the earliest scored in Grand Final history, coming after nine minutes.
A-League boss Greg O'Rourke said: "We are extremely disappointed at this failure of the VAR technology and we understand the disappointment and frustration of the Newcastle Jets, their fans and indeed all football fans.
"Whilst we understand that this happened only once this season it was at a most critical time. All parties desire the technology to be failure proof and that is what we will be striving for."
The game ended with controversy of another kind, with the Jets having striker Roy O'Donovan dismissed two minutes from time after his studs clattered into the face of Victory keeper Lawrence Thomas.
Thomas made some superb saves, particularly in the first half when the home side had 11 shots to Victory's three.
He made a reflex dive to deny O'Donovan's instinctive flick, then came up with an amazing double save. First he parried away Riley McGree's would-be equaliser before recovering in time to divert Jason Hoffman's point-blank follow-up shot away to safety.
The only goal came when Leroy George's swooping free kick found the head of James Donachie, who knocked it down for Barbarouses to fire past Glen Moss via a deflection off Johnny Koutroumbis.
Meanwhile, Australia are 1000/1 to win Group C at the 2018 World Cup.
The Socceroos are 11/8 to finish bottom of the group.
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