John Still cursed the defensive errors he believed gifted Pompey a Victoria Ground victory.
League Two’s bottom club had been leading through Ashley Hemmings’ first-half goal as Saturday’s fixture approached the hour mark.
Yet once Michael Doyle levelled, the Blues seized the initiative and ran out 4-1 winners.
It leaves Dagenham & Redbridge 11 points adrift of safety with only six matches remaining.
And for Still, the sight of three precious points slipping from a winning position was tough to digest.
He said: ‘We played very well in the first-half and started the second-half all right, but we made three massive errors.
‘I don’t think they won it, I think we lost it. The errors came at a stage in the second-half when we were looking to make changes.
‘Paul (Cook) couldn’t see a way out and I know he couldn’t because of the way that he was talking.
‘We said at half-time their best opportunity would come from restarts and I couldn’t see them breaking us down.
‘I don’t want to go into names, but the same player hasn’t marked twice for the goals from the free kicks. It’s absolutely killed us.
‘Being bold and brave isn’t about running, it’s about being brave. Don’t foul and you don’t give away free kicks.
‘The marking for the two goals from the same person is schoolboy and it’s something that’s been a problem since before I was here.’
The Daggers had been comfortably the better team in the first-half, deserving their lead.
Certainly a positive for Still to eke out of defeat.
He added: ‘In the first-half I thought we played really well and until they scored thought we played well.
‘Unfortunately they scored as Jamie Cureton was coming on but that’s life.
‘We set up well, showed commitment and everything we were doing was fine, but you have to play with your head.’