Matt Clarke and Kal Naismith were on target as Pompey returned to winning ways by beating Accrington at Fratton Park.
The centre-back headed home in just the second minute to ensure the Blues got their promotion challenge back on track.
But the hosts probably should have wrapped things up earlier, with some missed chances ensuring the finale was more stressful than it ought to have been.
Substitute Kal Naismith finally settled those nerves in stoppage-time following a quick break up the pitch.
Paul Cook stuck with the same side that were narrowly beaten at Wycombe the previous week, meaning the Eoin Doyle made his Fratton bow.
The hosts came charging out of the blocks and Marek Rodak made a fantastic save to deny Gary Roberts after the midfielder had been slipped through by Enda Stevens.
But the Blues did break the deadlock from the resulting corner, with Roberts collecting the ball back from Eoin Doyle and whipping in a cross that CLARKE headed home to open his account for the season.
Accrington had an interesting way of trying to find an equaliser with a shot straight from the restart, but the ambitious effort flew well wide.
It was Pompey doing most of the attacking, however, and Kyle Bennett fired narrowly past the post after being afforded space to run through the centre.
The hosts were winning plenty of corners, as Stanley struggled to get the ball to safety and threaten at the other end of the pitch.
And Clarke had another chance to find the net on 20 minutes, but this time headed over from a Roberts free-kick.
The lively Jamal Lowe was next to try his luck following some neat footwork inside the area, but his deflected strike was grabbed by Rodak at the second attempt.
Stanley then finally carved open a decent opportunity of their own, only for Sean McConville to waste it by curling wide when well-placed to trouble David Forde.
It was Pompey who finished the half on a high, however, and Clarke improvised with a scooped shot that was not far off target.
Half Time: Pompey 1 Accrington 0
The Blues did not sit back at the start of the second half and Gareth Evans’ excellent cross was flicked on by a defender, with the ball hitting Bennett and drifting wide.
And the winger then tricked his way past a couple of challenges, but his shot could not find a way through a sea of red shirts.
Rodak slipped as he tried to make a clearance on 54 minutes, with Amine Linganzi’s threaded pass for Roberts intercepted.
Stanley were trying their best to make inroads at the other end, but Sean Clare was off target, while Clarke blocked Billy Kee’s effort.
It was still the Blues looking most likely to add to the scoring, however, with Clarke somehow failing to convert another Roberts corner from close range.
Cook made a double switch on 66 minutes, with Bennett and Roberts withdrawn for Carl Baker and Naismith.
Accrington then came close to levelling moments later when Janoi Donacien’s header led to a scramble on the goal-line before the ball was eventually hacked to safety by Evans.
There were certainly a few more nerves as the clock ticked down and Pompey clung onto their slender advantage.
Evans made a couple of key clearances as Stanley, unsurprisingly, started to show more of an attacking threat.
The tiring Lowe was replaced by Noel Hunt for the closing stages, receiving a warm reception as he made his way off the pitch.
And Clarke had yet another chance to wrap things up late on, only to see his header saved by Rodak’s feet after meeting Baker’s corner.
But NAISMITH did secure the three points following a quick stoppage-time counter-attack, with Hunt releasing the winger, who surged up the pitch and coolly slotted home.
Pompey (4-2-3-1): Forde; Evans, Burgess, Clarke, Stevens; Linganzi, M.Doyle (c); Lowe (Hunt 85), Roberts (Naismith 66), Bennett (Baker 66); E.Doyle
Goals: Clarke 2, Naismith 90+2
Subs not used: O’Brien, T.Davies, Rose, Chaplin
Accrington (4-1-2-1-2): Rodak; Rodgers (McCartan 60), Beckles, Hughes, Donacien; Conneely (c); Clare (Clark 60), McConville; Husin (Boco 86); Kee, Edwards
Booked: Conneely, Donacien
Subs not used: Chapman, Sykes, Davies, Shaw
Referee: Gavin Ward
Attendance: 15,955 (48 away fans)