Paul Cook admitted he never saw Morecambe grabbing a Globe Arena goal.
Then goalkeeper Barry Roche grabbed an equaliser in the fourth minute of time added on to break the Blues’ hearts.
Pompey were contemplating a 1-0 victory following Gareth Evans’ 40th-minute opener – his seventh goal of the season.
It was an advantage the Blues boss didn’t see his side surrendering in a fixture in which they also struck the bar and had one cleared off the line.
But Roche would have the final say, heading home a corner in a packed penalty area to ensure it finished 1-1.
Cook said: ‘The game probably panned out exactly as we thought it would be, it’s a difficult night and you have got to give Morecambe credit for coming back.
‘But the reality is I never felt they were going to score truth be known. They have, though, we have drawn 1-1 and are hugely disappointed.
‘It was never going to be night for nice passing or nice football, it was a difficult night and we were 1-0 up and thought we’d done enough to win the game – and haven’t seen it out.
‘There wasn’t much quality at all, both teams had a difficult night in very cold conditions and a very bobbly pitch.’