Pompey suffered their first defeat of 2019 as they lost by a single goal to Blackpool in a largely turgid encounter at Fratton Park.
The action intensified following a soporific opening 45 minutes, but it was the visitors who struck through Chris Long.
And they held on for the closing stages as the Blues threw men forward in an ultimately unsuccessful attempt to find a leveller.
Kenny Jackett made one change from the side that secured a dramatic FA Cup victory against Norwich the previous week.
Andre Green – who came off the bench to net a stoppage-time winner at Carrow Road – was rewarded with a return to the starting line-up.
He replaced Ben Thompson following the midfielder’s recall by Millwall, meaning Gareth Evans dropped further back.
The first half was a drab affair that was greeted with more yawns than cheers from another packed Fratton crowd.
A Jay Spearing free-kick caused a few problems, but when the ball made its way to Callum Guy, he fired well wide.
Ben Heneghan then did well to turn the ball behind and stop Brett Pitman from capitalising on Jack Whatmough’s long pass.
A corner from Evans was nervously punched clear by Christoffer Mafoumbi on 20 minutes, but the Blackpool back-line were able to clear.
It was the visitors who looked more likely to break the deadlock during a bright 10-minute spell towards the end of the half.
Armand Gnaduillet had two chances in quick succession, but swiped at thin air from a Liam Feeney delivery and then headed a cross from Donervon Daniels straight into Craig MacGillivray’s arms.
And a second decent ball into the box from Daniels was turned over by Nathan Delfouneso at the near post.
Pompey finally started to threaten just before the break and a fine Pitman cross was just out of reach for Ronan Curtis.
Jamal Lowe had a shot deflected behind as the Blues began the second half with a lot more energy and attacking intent.
Blackpool then survived a couple of corners, while Nick Anderton would have been relieved to see Pitman’s cross evade a blue-shirted player after making a mess of his clearance.
There was an injury-enforced substitution on 55 minutes – but it was not any of the players who had to come off.
Referee Kevin Johnson limped forlornly to the sidelines to swap roles with fourth official Graham Kane.
Pompey continued to look more of a threat going forward, but their moves kept breaking down in the final third.
A good example was when Lowe cut the ball back for Green on the edge of the box, only for the loanee to take an air kick.
That proved to be his last contribution of note, with January signing Andy Cannon coming on for his debut on 64 minutes.
And the new arrival was soon involved in a lovely move involving Matt Clarke, Lowe and Curtis, with the latter seeing his effort blocked.
But it was Blackpool who took the lead on 75 minutes when Gnanduillet flicked the ball on for substitute Long to fire home.
Jackett immediately made his second change, with David Wheeler joining the forward line and Evans making way.
The hosts started to apply more pressure and Marc Bola bravely blocked Lowe’s drive, while Clarke’s cut-back somehow evaded his team-mates queuing up in the box.
Anton Walkes then swung in a fine left-footed cross, but Pitman’s glancing header was held by Christoffer Mafoumbi.
And the goalkeeper made a better save on 88 minutes to keep out Clarke’s hooked effort from a Lowe centre.
Pompey continued to throw everything at the Seasiders as the seconds ticked down, but they held on to take the three points back to the north-west.
Pompey (4-2-3-1): MacGillivray; Walkes, Whatmough, Clarke, Donohue; Evans (Wheeler 75), Naylor; Lowe, Green (Cannon 64), Curtis; Pitman (c)
Subs not used: Bass, Burgess, Haunstrup, May, Dennis
Blackpool (4-1-4-1): Mafoumbi; Daniels, Heneghan, Anderton, Bola; Spearing (c); Delfouneso (Long 68), Thompson, Guy (Pritchard 82), Feeney (Nottingham 88); Gnanduillet
Goals: Long 75
Subs not used: Boney, Bunney, O’Sullivan, Kirby
Referee: Kevin Johnson (Graham Kane 55)
Attendance: 18,403 (247 away fans)