Christian Burgess admitted the sickening nature of stoppage-time defeat at Rotherham was tough to take.
Pompey were hit with a late, late sucker punch to send them spinning to a 1-0 defeat to the Millers.
It was a painful first visit to the New York Stadium for the 1,471 supporters who travelled up the M1.
Much-maligned former striker Michael Smith provided the cross for ex-loanee Joe Mattock to head home in the 91st minute.
Burgess told how the outcome had floored him and his team after they defended so impressively.
There were blocks aplenty as the home side racked up the second-half corners.
But it counted for nothing after Mattock’s late intervention.
Burgess said: ‘It’s a tough one to take. They hurt the most.
‘It makes it worse that we’ve defended so well for 90 minutes.
‘We’ve done it for all that period, so to concede in that manner was sickening.
‘There were a few scrambles in the box but it felt like we defended well as a collective and deserved a clean sheet.
‘The point would have been massive and we would have had a completely different feeling afterwards.’
Mattock’s goal makes it the third time in four games Pompey have lost to a stoppage-time finish.
That’s an area of concern, with Burgess pinpointing an inability to keep the ball effectively as significant to the game’s outcome.
He said: ‘It’s not a lapse or a loss of concentration.
‘We had some chances on the counter but weren’t good enough on the ball to control the game.
‘We gave them a little too much possession and, in the end, the pressure told.
‘It’s hard to tell why we can’t get out when you play centre-half.
‘The boys put their bodies on the line and that clean sheet would have meant a lot.’
Burgess took heart from the way Pompey put their bodies on the line to repel the home side, but knows they need to reflect on the manner in which the game was lost.
That will be analysed in the coming days as Jackett’s men prepare to welcome high-flying Shrewsbury to Fratton Park on Saturday.
He added: ‘I don’t think it’s a pattern as such, more the ball didn’t fall for us sometimes.
‘The boys did work their socks off, but it’s one for the staff to go over and see how we can do better.
‘Obviously we need to go away and analyse if we can do anything better.
‘I’m proud of how we defended for 90 minutes and gutted for us and our fans over the late goal.’