Goals from Kal Naismith and Conor Chaplin saw Pompey secure victory against Hartlepool at Victoria Park.
But results elsewhere ensured their slim hopes of automatic promotion evaporated, with a spot in the play-offs against Plymouth now confirmed.
The game was a turgid affair before the break, but Naismith’s back-flick provided the spark needed to ignite the contest.
Both sides created plenty of chances after that, although it was Chaplin who came off the bench to wrap things up with a neat finish.
Paul Cook made one enforced change from the side that won at AFC Wimbledon earlier in the week.
Paul Jones – who came off with a thigh injury against the Dons – made way for Brian Murphy between the sticks.
That meant there was no keeper on the bench, while Jack Whatmough made a welcome return to the squad after more than a year out following a knee injury.
The weather before kick-off was certainly unpredictable with hail and snow eventually making way for warm and sunny conditions.
Unfortunately, there was nothing to get particularly excited about once the football got underway.
It began promisingly enough, with Gary Roberts’ effort cannoning into Naismith and deflecting just wide.
But the game soon entered a lull, with the hosts – who had nothing but pride to play for – not showing too much ambition.
There was a free-kick from Nathan Thomas that clipped the top of the wall and flew behind for a corner.
The home fans started to grow frustrated, however, as there was nobody getting into the box to meet some dangerous crosses.
Roberts was doing his best to inject some urgency into proceedings, with a couple of incisive balls that were cleared by the Pools defence.
Pompey suddenly had a couple of decent openings just before the break, as Michael Smith met Christian Burgess’ cross and sent a header looping over the bar.
Roberts then put Gareth Evans away with a fine threaded pass, but he was denied twice in quick succession by former Blues loanee Trevor Carson.
Hartlepool United 0
The second half initially failed to see an increase in entertainment, with both sides appearing to go through the motions.
A long-range effort from Luke James that rolled comfortably into Murphy’s arms was as close as either came to breaking the deadlock early on.
But the Blues did forge ahead as the game finally conjured up a moment of quality on 57 minutes.
Roberts played a fine pass across to Evans, whose low cross into the box was nonchalantly flicked home by NAISMITH in front of the delighted travelling support
It was almost the home fans celebrating moments later, though, as Billy Paynter burst through on goal and was brilliantly denied by Murphy.
There were suddenly chances galore and Roberts fired a shot into the side netting, while Carson stood his ground to make a save after Smith went one-on-one with the keeper.
Cook made his first chance on 64 minutes, as goal hero Naismith made way for Adam McGurk in the Blues’ attack.
It was a Hartlepool sub that almost scored soon after, though, as – just seconds after entering the pitch – Rhys Oates was denied by another super stop from Murphy.
The hosts were starting to look dangerous and Jones got the ball caught under his feet before his eventual shot was blocked.
A second switch followed on 73 minutes as Chaplin replaced Smith, with the latter given a rousing reception as the curtain came down on his loan spell.
But Hartlepool were still causing a threat and Oates should at least have found the target from close range when he met Thomas’ cross.
CHAPLIN wrapped up the victory on 85 minutes, however, when Enda Stevens cut the ball back for him to coolly steer into the bottom corner.
And there was more good news when Whatmough made his long-awaited return by replacing Christian Burgess for the final few minutes.
Hartlepool (4-1-4-1): Carson; Magnay, Bates (R.Jones 50), Jackson, D.Jones; Featherstone; James, Woods (Gray 76), Hawkins, Thomas; Paynter (c) (Oates 68)
Subs not used: Bartlett, Walker, Richards, Bingham
Pompey (4-2-3-1): Murphy; Freeman, Burgess (Whatmough 89), Barton, Stevens; Hollands, Doyle (c); Evans, Roberts, Naismith (McGurk 64); Smith (Chaplin 73)
Goals: Naismith 57, Chaplin 85
Subs not used: Davies, Haunstrup, Close, Tollitt
Referee: Eddie Ilderton
Attendance: 5,046 (933 Pompey fans)