Ben Close conceded Pompey perhaps could have been more patient in their pursuit of a match-winner against Peterborough.
Kenny Jackett’s men looked like they were going to take the League One automatic promotion race to the final day of the season after battling from two goals down against the Posh.
Lee Tomlin and Ivan Toney put the visitors in front within 28 minutes but goals either side of half-time from Close and Christian Burgess drew the Blues level.
It was the home side who stayed on the front foot and put Peterborough under a barrage of pressure.
In an incredible two minutes, however, Viv Solomon-Otabor had a goal disallowed for offside before Toney’s scored at the other end with 15 minutes remaining to condemn the Blues to a play-off finish.
Close admitted Pompey were punished by Peterborough’s potent attack.
He said: ‘They have got some very good attacking players.
‘Maybe we did throw too many players forward at that point and we will look at what we can do better.
‘At that point, it was 2-2 and we were on the front foot looking to score the third.
‘Maybe we should have been staying patient to get the third goal.
‘We didn’t get our noses in front at all and that’s what we were expecting to do.
‘Peterborough have got good attacking players and were happy to maybe soak it up and break.
‘They did that a few times and punished us.’
Close netted his eighth goal of the season in the 38th minute when his right-foot shot found the top corner.
The Southsea midfielder almost grabbed a second after the interval but had one effort blocked while he sent a dipping volley just over the crossbar.
Close added: ‘That’s eight for the season and seven in the league.
‘It’s always nice to score. I hit the ball straight into the ground and the pitch was wet enough for it to fly into the back of the net.
‘It was great to see and at that point I thought “We have got a real chance here.” Unfortunately it wasn’t to be.
‘In the second half, it was a good block but probably an easier chance than the goal.
‘I hit the second one nice and it would have been nice to have seen it fly in.’