Liam Lawrence revealed Kevin Friend admitted he was wrong to award Reading a decisive penalty in Pompey’s Madejski Stadium defeat.
The Leicestershire official sent Ricardo Rocha off and pointed to the spot after Shane Long was sent tumbling in the 37th minute.
Reading’s top scorer then netted the penalty to give the hosts an unassailable 2-0 lead.
That moment incensed Pompey’s players and management, especially after watching a video replay afterwards.
The video replay of Rocha’s challenge prompted Pompey boss Steve Cotterill to approach Friend at half-time to show him footage on a laptop.
Lawrence claims the referee then conceded he had made a mistake.
Not that it is any consolation for the Blues, the defeat dealing a severe body blow to their play-off aspirations.
Pompey’s skipper said: ‘One of our guys records everything and it was on the laptop. We looked at it and it was outside the box.
‘So the gaffer has gone into the referee at half-time and shown him the laptop and the referee has accepted it.
‘It was yards outside the box.
‘If he wants to send him off then fair enough but it’s not even a pen.
‘I think he accepted the decision was wrong. He knew he made a mistake.
‘But we came out for the second half and the mistakes carried on.
‘You’re just looking for some consistency, and on Saturday I think the referee has let himself down. He’s been poor.
‘I don’t normally come out and hammer referees, and before the game I was glad we had got him (Friend) because I do think he is a good referee.
‘But on Saturday he made some decisions that baffled me and the rest of us.
‘Now I’m captain I have to try to restrain myself, whereas before I used to scream at referees and the rest of it.
‘But now I have to be seen as a cooler head, I just let him get on with it.
‘It’s an absolute comedy of errors that absolutely killed us.’
While Friend received criticism, at the other end Pompey didn’t help their cause by missing a string of chances.
Dave Kitson – on his Reading return – was the chief culprit during a profligate first half.
Meanwhile, Royals keeper Alex McCarthy produced a stunning point-blank stop to thwart him on another occasion.
Kitson’s misses ultimately proved costly as Reading ran out winners to dent the play-off hunt for Cotterill’s men.
But Lawrence was quick to defend his team-mate.
He added: ‘Kits could have had a couple of goals.
‘He said to me afterwards “I’ve been shocking today”.
‘In the second half I thought he did a lot better and his hold-up play was good and he got himself in the box.
‘But sometimes things don’t go for you, especially against your old clubs.
‘Sometimes you can’t score or not do so well but I thought he did alright on Saturday.’