Pompey probably would have taken a point if it was offered at half-time of their League One contest at Accrington.
But after going in for the interval two goals down, they turned it round to lead 3-2 in the final seconds.
An acrobatic John Marquis finish looked to have completed the comeback, with the striker having already reduced the visitors’ deficit before Ryan Williams levelled.
Instead they had to settle for a point, with an unfortunate ricochet ensuring the ball flew off the number nine and into his own net.
A draw was still enough to take Pompey back into the play-off places, but Danny Cowley felt the overall performance left a lot to be desired.
The Blues boss said: “It’s pretty heart-breaking and a difficult game to summarise after we fought back from 2-0 down to get into the lead.
"The second goal we let in is unacceptable for us and the 10 minutes before half-time simply weren’t good enough for Portsmouth Football Club."
“But we’ve given a cheap, unnecessary free-kick away and then haven’t been able to defend our box – which we couldn’t do all night. To concede such a soft goal is a tough one to take.
“There were a couple of gilt-edged opportunities when it was 0-0 that we were unable to convert, although the massive news for us is that John is back in the goals.
“We conceded what was a brilliant first effort for them and you have to give credit to John Coleman and his staff because they find terrific players with very little resources.
“They’ve got some of the best in this league and I thought Colby Bishop and Dion Charles up front were huge.
“But the second goal we let in is unacceptable for us and the 10 minutes before half-time simply weren’t good enough for Portsmouth Football Club.
“We got the players in and spoke the truth, then came out and showed character, grit, resilience and fight.
“There were three goals for us, but if you want to be a good team then you have to see it out – and we couldn’t.”