Pompey won their final away game of the season at Mansfield to keep title hopes alive.
A fractious contest was settled just before the hour mark with a goal that Carl Baker and Conor Chaplin both claimed.
The Stags thought Matt Clarke should have been dismissed earlier in the second half and could not make their late pressure count.
Paul Cook made three changes from the side that beat Cambridge on home soil the previous week.
Chaplin, Christian Burgess and Danny Rose all returned, with Nicke Kabamba, Jack Whatmough and Stanley Aborah – the latter of whom had been struggling with a neck injury – dropping to the bench.
The hosts were desperately searching for a play-off spot, so it came as no surprise that they showed more urgency in the opening stages.
A free-kick led to a scramble in Pompey’s box and Lee Collins’ cross ricocheted off Rhys Bennett and straight into David Forde’s arms.
Another set-piece from the hosts was quickly given to the familiar-sounding Danny Rose, whose low drive was comfortably stopped by Forde.
In truth, however, neither side was able to get out of second gear in a drab half that yielded very few clear-cut chances.
Mansfield’s Rose had another effort easily dealt with by Forde, while Kal Naismith took a swipe at thin air and ended up on his backside – drawing laughter from Cook in the technical area.
Gareth Evans was looking lively for the Blues and he dragged a shot wide after stealing the ball from Alex MacDonald.
Naismith then had the best chance for the visitors with a fierce drive that was heading for the top corner until being beaten behind by Jake Kean.
Kyle Bennett also enjoyed an impressive run along the edge of the box, but his shot did not cause the Stags keeper too much trouble.
Mansfield Town 0
The first half might have been forgettable, but the second exploded into life in the opening few minutes.
Mansfield’s Danny Rose caught Clarke dithering and was brought down by the defender, who would have just had Forde to beat.
The home crowd – and players – were baying for a red card and left furious when referee Lee Swabey instead pulled a yellow one from his pocket.
There was more bad news for the Stags moments later when Rhys Bennett found the net, only to have his celebrations cut short by an offside flag.
But the Blues did break the deadlock on 57 minutes – even if there was some confusion about who should claim it.
BAKER played a neat one-two with Naismith and curled a shot past the grasp of Kean and into the net.
He was certainly credited with the goal, although it might have got a touch off Chaplin – not that it mattered to the celebrating travelling fans.
There was certainly a fractious atmosphere, not helped by a late challenge by Ben Whiteman on Bennett.
That led to some pushing and shoving, with Swabey booking both Whiteman and Bennett, as well as Enda Stevens.
Mansfield knew they needed at least a point, so poured forward in search of an equaliser and MacDonald should at least have hit the target after being picked out at the far post.
But Chaplin then had an opportunity at the other end of the pitch and dragged his shot narrowly past the post.
MacDonald aoon had another chance for the hosts, but his effort was well saved low to his left by Forde.
Whatmough replaced Chaplin on 69 minutes as Cook looked to shore things up at the back and was immediately called into action to head clear a free-kick.
Cook completed his changes with the introductions of Gary Roberts and Aborah for Baker and Bennett respectively.
But Mansfield substitute Matt Green should have levelled soon after when he was sent through on goal and lifted the ball over Forde – but also over the net.
It was backs to the wall for Pompey as their hosts poured forward in search of a leveller, but that left spaces at the other end.
Naismith should have taken one of them late on, but could not keep his shot down after being teed-up by Roberts.
It mattered not, however, as the Blues saw out six minutes of stoppage-time to maintain hopes of adding some silverware to their promotion party.
Mansfield (4-4-2): Kean; White, Pearce, Bennett, Benning; Whiteman, Collins (c) (Green 68), Byrom, MacDonald (Hoban 86); Coulthirst, Rose (Taft 83)
Booked: White, Whiteman, Bennett, Pearce
Subs not used: Jensen, McGuire, Potter, Hamilton
Pompey (4-2-3-1): Forde; Evans, Burgess, Clarke, Stevens; Rose, M.Doyle (c); Baker (Roberts 77), Naismith, Bennett (Aborah 77); Chaplin (Whatmough 69)
Goals: Baker 57
Booked: Baker, Clarke, Stevens, Bennett, Aborah
Subs not used: O’Brien, Linganzi, Lowe, Kabamba
Referee: Lee Swabey
Attendance: 6.819 (1,459 Pompey fans)