Pompey struck twice in the second half to continue their excellent start to the season with victory at struggling Burton.
They had to remain patient before getting a stroke of luck when Sam Hughes turned the ball into his own net.
The winless Brewers then had a goal disallowed before Colby Bishop struck to reward the large travelling faithful.
Danny Cowley made one enforced change from the side that beat Peterborough on home soil 10 days earlier.
Joe Rafferty missed out with a stomach problem, so Connor Ogilvie – who was absent from the Posh contest after becoming a father – filled in at right-back.
Before kick-off, a minute's silence was held to remember Her late Majesty the Queen Elizabeth II, which was followed by the national anthem.
Pompey started brightly and were looking to commit plenty of men forward in the contest’s opening stages.
And they almost had an opening when Dane Scarlett beat a couple of challenges before flashing a shot inches past the post.
Ogilvie then sent a superb cross towards the back post, where a Ronan Curtis header was blocked by Tom Hamer.
The danger was not over for the Brewers, however, and Ben Garratt did well to scoop the loose ball clear before Bishop could pounce.
But the match began to fade after that bright start and a number of niggly fouls halted the visitors’ flow.
Owen Dale livened things up by cutting onto his left foot and fizzing in a shot that was deflected narrowly wide.
The resulting corner eventually found its way to Curtis on the edge of the box, but he was unable to make a clean connection and the ball bobbled past the post.
There had been little to trouble the Blues at the other end, although a stray Josh Griffiths clearance found Joe Powell and Sean Raggett had to come to the rescue with a timely block.
Half Time: Burton 0 Pompey 0
There was controversy shortly after the restart when a teasing Ogilvie delivery had to be turned behind for a corner.
When the ball was sent into the box there looked to be shoves on a couple of Pompey players, but referee Robert Lewis was not interested.
So the visitors would have been particularly frustrated if Davis Keillor-Dunn’s effort moments later had curled the right side of the post.
Pompey were showing more ambition, though, and Dale did brilliantly to skip past a couple of challenges on the right.
Garratt was unable to keep hold of the winger’s cross, but did well to get to the loose ball before Bishop.
And the deadlock was broken soon after, with Marlon Pack combining well with Ogilvie on the right and sending in a low delivery.
The intended target was Scarlett at the near post, but the ball flew past him and ricocheted into the net off unfortunate defender HUGHES.
Pompey kept pushing in search of more goals and a long-range attempt from Ogilvie fizzed just past the post.
Scarlett did have the ball in the net with a neat finish on 65 minutes, but Lewis decided he had committed a foul in the build-up.
Burton started to show some more urgency and a long throw into the box from Hamer should have led to the equaliser.
The ball was flicked on towards Sam Winnall at the back post, but the striker somehow failed to find the target from just a couple of yards out.
Cowley responded with a double substitution to bring some fresh legs onto the pitch, as Scarlett and Curtis made way for Joe Pigott and Josh Koroma.
It looked as though the Brewers had finally made their late pressure count, when Musatpha Carayol burst through a couple of players and teed-up Victor Adeboyejo to bend the ball home.
The home faithful saw their celebrations cut short, though, when they spotted a flag raised for offside.
And Pompey rubbed salt into the wound by making sure of the points soon after, as a Dale delivery was neatly flicked home by BISHOP.
Burton (3-4-3): Garratt; Hughes, Brayford (c), Borthwick-Jackson; Hamer, Taylor (Thorpe 84), Butcher (Winnall 69), Keillor-Dunn (Carayol 69); Powell, Gilligan (Oshilaja 73), Adeboyejo
Booked: Gilligan, Taylor
Subs not used: Sinisalo, Onyango, Lakin
Pompey (4-4-2): Griffiths; Ogilvie, Morrison, Raggett, Robertson (c); Dale (Hackett 87), Pack, Lowery, Curtis (Koroma 77); Scarlett (Pigott 77), Bishop (Mingi 88)
Goals: Hughes 59 (og), Bishop 86
Booked: Raggett
Subs not used: Oluwayemi, Swanson, Morrell
Referee: Robert Lewis
Attendance: 2,945 (1,000 Pompey fans)