Michael Appleton pinpointed the timing of Burnley’s second goal as the instigator of their embarrassing Fratton Park capitulation.
Pompey’s survival hopes took a battering as they slumped to a 5-1 defeat against Eddie Howe’s side during a shocking second-half display.
The hosts had been level at the break following an impressive opening 45 minutes.
But Danny Ings’ goal, 75 seconds after the restart, turned the Fratton match on its head.
Appleton believes that second Burnley goal knocked the stuffing out of his side in the latest of a long line of must-win matches.
Subsequently, a hat-trick from Charlie Austin inflicted a 5-1 hammering as Pompey’s bid to remain in the Championship took a massive body blow.
And afterwards the Blues boss bemoaned the timing of what he considered to be the decisive moment.
He said: ‘The first half was probably as good as it was on Tuesday night, from a performance point of view.
‘We just never took the opportunities we created.
‘I think we were the miles better side in the first half. I can’t remember them getting into our half that often to be honest.
‘But we weren’t clinical enough. We got fantastic opportunities time and time and time again.
‘We are at the wrong end of the season to not take opportunities we have made, so we got punished for it and punished in a big way.
‘As soon as that second goal went in, it was almost as if it completely deflated the players.
‘It was a big blow.
‘A goal so soon after the break makes life very difficult no matter what the situation is.
‘We knew we had to start the second half in the same tempo we did in the first half, so to lose the goal so quickly and the manner in which it came was poor.
‘For whatever reason – and we will look back at the video and address it as best we can – it really did seem to affect the players.
‘All of a sudden players started to turn their back on the ball, they didn’t want to get on the ball and started refusing forward passes, which, to be fair, hasn’t been like us recently.
‘There were a lot of really good performances in the first half and then the second half some really, really poor performances and I can pretty much single out every single player.’
Substitute Austin, a Wessex League player in 2009, added an emphatic look to the scoreline, with his 16-minute hat-trick.
But Appleton was disappointed his side had not made their superiority pay during the first-half.
And he was also angry over the manner of Kieran Trippier’s 16th-minute opener.
He added: ‘I was very frustrated with their first goal.
‘It is something they have used quite a few times over the last 18 months and something we have shown the players a dozen times on the video.
‘But it still doesn’t disguise the fact we lost too many personal battles in the second half and didn’t do enough to ever stay in the game.
‘Then they hit us on a couple of counter-attacks towards the end and got a bit of luck with the third goal – which was a blatant handball – but these things happen.
‘We have an opportunity to reflect and lick our wounds, come in today, train as we normally would and prepare for a very, very tough game in Southampton.’