An excellent second-half strike from Jobi McAnuff sent Pompey spinning to a hugely-frustrating 1-0 loss to Leyton Orient.
McAnuff – who has family from Portsmouth – decided it with a fine 25-yarder in the 53rd minute on a depressing afternoon at Fratton Park.
There were boos on the full-time whistle on a missed opportunity for Paul Cook’s side, with many of their promotion rivals seeing their games postponed.
Pompey fall to seventh with the loss, with Accrington Stanley having two games in hand below them.
The Blues had an early chance as Marc McNulty fired at Alex Cisak from 25 yards.
Sammy Moore’s shot was deflected over after nine minutes as Orient replied.
It was game short on chances though, as Orient were proving hard to open up with the Blues playing a 4-4-2 formation.
The game sprang to life after 30 minutes as Smith and Bennett combined to free McNulty, but Cisak smothered his shot.
Bennett then headed wide from 10 yards as the home crowd found their voice, before blazing over after nutmegging Jack Payne.
Moore flashed a header just wide from Jobi McAnuff’s pass at the end of a half where Pompey didn’t manage to find their rhythm.
McAnuff put in a dangerous cross which was cleared before Freeman’s shot was deflected wide as the second half started at a pace.
Then Kevin Nolan had the best chance of the game when he hit the bar after Payne’s shot was blocked by Burgess.
But it was the visitors who took the lead after 53 minutes through a peach of goal from McAnuff.
There appeared to be little danger on as the ball fell to the Orient man, but an excellent hit from 25 yards left Ryan Fulton with no chance.
There were further chances for Orient to add to their lead as Simpson first blazed over from seven yards before heading at Fulton from inside the six-yard box.
Pompey threw on Conor Chaplin, Adam McGurk and Gareth Evans in search of the leveller as Cook switched to a 4-2-3-1.
Chaplin headed over at the death from inside the six-yard box from McGurk’s headed pass.
But there was no late drama this time as Pompey fell to a loss which disappointed.