It was a contest befitting the soulless atmosphere inside a mostly empty Bloomfield Road, with hardly any chances at either end of the pitch.
But it was the Tangerines able to celebrate all three points, courtesy of a second half strike from Keshi Anderson.
Kenny Jackett made one change from the side that drew with Oxford in the last league outing seven days earlier.
Ellis Harrison dropped to the bench to make way for Ryan Williams, who was positioned out on the right, with Marcus Harness joining John Marquis up front.
There was not much to trouble either keeper in an opening 45 minutes that was extremely short on anything that could truthfully be called exciting.
Blackpool dominated possession and territory in the early stages, but were unable to penetrate the Blues back-line.
A Sullay Kaikai effort was bravely blocked by Sean Raggett, while Tom Naylor slid in to prevent Anderson capitalising on the loose ball.
Craig MacGillivray then comfortably dealt with a James Husband header after Kaikai’s corner had been flicked on for the defender.
Pompey began passing the ball around nicely as they settled into the contest, without making any inroads in the final third.
The first decent chance came at the opposite end on 24 minutes, with MacGillivray turning CJ Hamilton’s angled drive into the side netting.
As the half continued, the visitors began posing a few more problems, although could not quite find that final killer ball.
Harness did brilliantly to control Andy Cannon’s pass, only to see his attempted threaded ball for Marquis intercepted.
Their best opportunity arrived when Ethan Robson failed to clear inside his own box and Marquis dug out a shot that rolled narrowly past the post.
MacGillivray made a simple save to deny Jerry Yates as the seconds ticked away, then came quickly off his line to beat Hamilton to the ball.
Any hopes that there would be an improvement in the drama levels straight after the restart were quickly extinguished.
Instead, the game continued in niggly fashion, with plenty of appeals from both sides for free-kicks – most of which were ignored by referee Joshua Smith.
Jackett tried to inject some fresh energy into his side with a double substitution just past the hour mark.
Ben Close and Harrison were the men chosen to lift the visitors, with Cannon and Ronan Curtis making way.
Williams got himself into the path of Hamilton’s shot on 64 minutes, while Daniel Ballard was then booked for fouling Marquis as the Blues tried to launch a quick break.
But Blackpool then broke the deadlock moments later, with Yates wisely leaving Hamilton’s low centre for Anderson to drive into the net.
Cam Pring soon came on for Williams and took up residence just in front of Lee Brown on the left-hand side.
The Blues were trying to find a way back and Marquis hit two efforts off target, the second coming after Naylor had found him with a fine lofted pass.
Pompey were huffing and puffing in search of an equaliser, but Chris Maxwell was still a virtual spectator between the sticks.
Blackpool were at least forcing MacGillivray to get his gloves dirty and the keeper got down low to his right to push clear Kaikai’s shot.
The game was threatening to end with a whimper, but Marquis finally forced Maxwell into action in stoppage-time.
And after the keeper pushed away his shot, the resulting corner saw a spot of pinball in the box before the hosts were finally able to clear the danger.
Blackpool (4-4-2): Maxwell (c); Turton, Ekpiteta, Ballard, Husband; Hamilton, Robson, Dougall, Kaikai; Yates (Madine 82), Anderson (Woodburn 76)
Goals: Anderson 64
Booked: Ballard, Madine, Kaikai
Subs not used: Sims, Gabriel, Gretarsson, Mitchell, Kemp
Pompey (4-4-2): MacGillivray; Johnson, Whatmough, Raggett, Brown; Williams (Pring 66), Naylor (c), Cannon (Close 61), Curtis (Harrison 61); Marquis, Harness
Booked: Marquis, Brown
Subs not used: Bass, Mnoga, Nicolaisen, Hiwula
Referee: Joshua Smith