Conor Chaplin's second goal as in many matches couldn't prevent Pompey from falling to a defeat against Blackburn.
The academy product equalised for the Blues shortly into the second half, but Adam Armstrong's second of the game just three minutes from time condemned Kenny Jackett's outfit to a 2-1 defeat.
The visitors had Lewis Travis sent off in stoppage-time, but Pompey were unable to find an equaliser.
Blackburn almost opened the scoring within five minutes but Luke McGee smartly stopped Dominic Samuel's effort with his legs.
Pompey had their first sight on goal in the 10th minute when Dion Donohue's 25-yard shot was well saved by David Raya.
In the 21st minute, the visitors broke the deadlock.
Richie Smallwood's cross from the right found its way to Armstrong at the back post and he guided his effort home from close range.
But the Blues responded well, with Brett Pitman and Gareth Evans both having efforts saved.
Anton Walkes almost ensured Jackett's troops went into the interval level but his curling left-footed effort on the stroke of half-time whistled beyond the far post.
But Pompey had to wait just five minutes into the second period to get their leveller.
Donohue's cross fell to Walkes, whose smart hook across goal found Chaplin lurking inside the six-yard box and he calmly headed home.
And the hosts could have taken the lead just a minute later when keeper Raya and Ryan Nyambe failed to communicate with each other.
The loose ball fell to Pitman, who had the goal at his mercy on the edge of the box, but couldn't steer his shot on target.
Walkes had a superb chance to put the Blues in front 13 minutes from time when he was slipped in by Jamal Lowe, but the Spurs loanee's angled right-footed shot narrowly went wide of the far post.
And Blackburn grabbed all three points in the 87th minute.
Darragh Lenihan's cross was deflected off Matt Clarke and there was Armstrong to prod home from close range.
Rovers ended the game with 10 men when substitute Travis was sent off for a wild lunge on Nathan Thompson.
But the Blues were consigned to a defeat and drop to ninth in the League One table.