Joe Pigott came off the bench to score a penalty and ensure Pompey’s fine winning run would continue.
They dominated for long periods against Bristol Rovers at a sunny Fratton Park and a firm Connor Ogilvie header provided an interval lead.
But it looked as though they would have to settle for a point after a mistake at the back allowed Aaron Collins to level.
The Blues piled on the pressure, however, and Pigott won a late spot-kick that he stepped up to convert.
Owen Dale then wrapped things up with a diving header in stoppage-time to ensure Pompey would deservedly claim another three-point haul.
Danny Cowley made two changes from the side that thrashed Cambridge on home soil earlier in the week.
Michael Jacobs was rewarded for coming off the bench to score that night with a starting berth, while Louis Thompson also returned.
That meant Dane Scarlett and Tom Lowery dropped to the bench, where they were joined by fit-again skipper Clark Robertson.
Pompey looked the more threatening side from the start, although a looping Sean Raggett header did not overly trouble James Belshaw.
The hosts were playing some intricate passing football and just looking for that final key pass when they approached the opposition area.
One of those moves ended with the ball at the feet of Ronan Curtis – partnering Colby Bishop up front – but he was denied by a fine Lewis Gibson block.
The Blues were dealt a blow on 19 minutes, however, when Thompson was challenged from behind by Glenn Whelan and left writhing in agony on the pitch.
He was soon receiving oxygen before eventually being stretchered from the field, receiving warm applause from the stands.
Lowery was brought on to replace him, but the Fratton faithful showed their displeasure when referee Gavin Ward decided a yellow card was sufficient punishment for Whelan.
When the game eventually restarted, Paul Coutts received the ball from Collins and fired in a low shot that was cleared from the line by Raggett.
But the Blues were soon back on the attack and a Dale snap-shot from outside the box flew narrowly past the post.
And they broke the deadlock on 32 minutes, as a Jacobs corner was met by OGILVIE, whose bullet header flew into the top corner.
Pompey remained on the attack and were searching for another route through an organised Pirates back-line.
They won a trio of corners during the lengthy stoppage-time period and the third from Jacobs ended up finding Michael Morrison at the back post, but he could not hit the target.
Half Time: Pompey 1 Bristol Rovers 0
Set-pieces were proving problematic for the visitors and it continued when the action restarted after the interval.
A corner from Jacobs was missed by Ogilvie and ricocheted off Raggett, with Belshaw having to turn the ball behind.
Jacobs then sent another centre into the mixer and the header from Curtis took a deflection before being headed off the line by former Blues striker John Marquis.
But a rare mistake at the back saw Rovers grab an equaliser just past the hour mark, with Marquis stealing the ball from Raggett and teeing-up Collins to slot home.
Cowley soon freshened up his forward line, as the tireless Curtis was withdrawn and replaced by Scarlett.
He might have scored moments later, but Lowery’s fine cross just cleared the striker’s head and was volleyed narrowly over by Dale.
A free-kick then led to absolute chaos in the visitors’ box and Pompey players were lining up to try their luck.
There were opportunities for Jacobs, Ogilvie and Marlon Pack, but nobody could force the ball through a sea of bodies.
Cowley then made a final throw of the dice with a double switch, as Jacobs and Bishop made way for Reeco Hackett and Pigott.
And it soon paid dividends, with the pair both involved with the goal that saw Pompey restore their lead.
Hackett was allowed to drive forward and unleash a thumping shot that Belshaw could only parry away.
PIGOTT was shoved by Harry Anderson as he tried to convert the loose ball and Ward pointed to the spot, with the striker calmly rolling home the penalty.
The visitors thought they should have won a spot-kick of their own soon after, but the officials did not agree with Collins’ protests that he had been pushed by Joe Rafferty.
And any doubts vanished in stoppage-time, as Pigott laid the ball off for Scarlett, who whipped in a fine cross that DALE converted with a diving header.
It might have got even better for the Fratton faithful, as their side continued to attack in the closing stages, but Rovers were able to limit the damage.
Pompey (4-4-2): Griffiths; Rafferty, Morrison, Raggett (c), Ogilvie; Dale, Pack, Thompson (Lowery 24), Jacobs (Hackett 77); Curtis (Scarlett 64), Bishop (Pigott 77)
Goals: Ogilvie 32, Pigott 82 (pen), Dale 90+2
Booked: Pack, Morrison, Scarlett
Subs not used: Oluwayemi, Swanson, Robertson
Bristol Rovers (3-3-3-1): Belshaw; Hoole, Connolly, Gibson (Kilgour 76); Coutts (c), Whelan (Anderson 46), Finley; Evans, Rossiter (Loft 74), Collins; Marquis (Saunders 79)
Goals: Collins 61
Booked: Whelan, Gibson, Rossiter, Finley, Coutts
Subs not used: Jaakkola, Gordon, Lawrence
Referee: Gavin Ward
Attendance: 18,842 (1,843 away fans)