Cardiff boss Malky Mackay says the referee who made the "horrendous decision" that "cost" his side victory over Millwall has admitted his mistake.
Cardiff's Aron Gunnarsson thought he had won Saturday's goalless draw when he headed in Liam Lawrence's free-kick.
Referee Tony Bates ruled out the second-half effort as assistant Andrew Rodda adjudged Gunnarsson pushed Millwall's Jimmy Abdou in the build-up.
"He called me back today and apologised because he's seen it," said Mackay.
"He watched it seven or eight times and said there's absolutely nothing wrong with it."
Mackay believes Bates' admission justifies his post-match reaction following a game in which the Bluebirds' Championship play-off bid continued to falter.
In the immediate aftermath of the game Mackay said: "We have seen the goal again and it's a horrendous decision.
"It is the third goal given against us by a linesman [this season].
"The previous two, the League Referees Association have phoned up after we showed them the DVD and admitted the linesman had got it wrong.
"Well they are going to be doing the same again, the minute they get this DVD.
"It was a dreadful decision.
"Sometimes games are won and lost on things like that and Millwall are fighting for the lives - sometimes it comes down to one decision.
"We opened them up on a set-piece, we scored a perfectly good goal and from 50 yards, the linesman has given it as a pull - and when he sees it again he will be absolutely embarrassed at the decision.
"Gunnarsson only has his eyes on the ball and their player pulls him down for [what should have been a] penalty. Everyone has said the same."
Iceland international midfielder Gunnarsson had a goal disallowed earlier on in the season and Mackay claims Cardiff have been wrongly denied four points that would now have put the eighth-placed Bluebirds in fourth.
But Cardiff, who have won just twice in 14 games, are two points adrift of the play-off places after failing to win their fifth successive home game.
"It is hugely frustrating," said Mackay.
"You need it to be a level playing field and it wasn't on the basis of that goal going in and it not being given."
BBC Sport have contacted the Football League for a comment on Mackay's claim.
Millwall had the ball Cardiff's net before Gunnarsson beat Millwall keeper Maik Taylor, however Lions striker Andy Keogh's effort from Tony Craig's cross was disallowed for offside.
"He is way offside when the ball goes in the net," added Mackay.