Dane Scarlett was on target to earn Pompey a deserved win at Port Vale and send them top of the League One standings.
The Tottenham loanee netted the only goal of the game midway through the first half to open his account for the club.
But it was a game that the visitors dominated for long periods and the Valiants rarely looked like grabbing an equaliser.
Danny Cowley made two changes from the side that beat Bristol Rovers in the last league game a week ago.
Tom Lowery came in for Louis Thompson, who suffered a broken leg in a nasty challenge against the Pirates.
And Dane Scarlett replaced Michael Jacobs, which meant Ronan Curtis returned to his usual position wide on the left.
Meanwhile, Joe Morrell was a welcome addition to the bench, having recovered from a groin problem.
There were a couple of notable milestones in the visitors’ side, with Marlon Pack making his 500th career league appearance and Sean Raggett given a 150th outing for Pompey.
And there was a regular face in the opposition line-up, as former Fratton striker Ellis Harrison led the line.
There was a memorial before kick-off, with the names of supporters from both clubs who have passed away recently read out.
A wreath was laid by Andrew Cullen on behalf of the Blues, while there was a minute’s silence once the players had entered the pitch.
The visitors were looking to get a midweek cup exit out of their systems and made a quick start in Staffordshire.
Lowery stole possession and played a neat one-two with Colby Bishop before releasing a pass for Scarlett.
The teenager looked to cut the ball back for Lowery, who had raced into the box, but it was a bit too close to the midfielder, ricocheting off him and flying wide.
Owen Dale then skipped past a defender on the right and whipped in a cross that was nodded off target by Curtis at the far post.
But the Blues were soon forced into a change, as an earlier clash of heads between Michael Morrison and Harrison saw the defender replaced by Clark Robertson.
Port Vale looked to respond after surviving that spell of pressure and might have taken a fortunate lead.
A long throw caused chaos in the area and when Raggett tried to clear the danger, the ball smashed into Robertson and bounced behind.
Harrison thought he should have been awarded a penalty after tangling with Connor Ogilvie from the resulting corner, but referee Craig Hicks did not arrive.
Instead it was Pompey who broke the deadlock on 25 minutes, as lovely Pack pass sent SCARLETT racing away.
The striker looked to have taken one touch too many, but was still able to bundle the ball over the line.
A series of crosses at the other end caused a few problems and the third of them was nodded over by Connor Hall.
But Pompey kept pushing and were pressing their opponents high up the pitch to try to force mistakes.
That almost happened when Scarlett tried to capitalise on a weak Hall back-pass, with keeper Jack Stevens just about getting to the ball first.
Half Time: Port Vale 0 Pompey 1
The visitors showed their intention to keep attacking right from the restart and a deep Joe Rafferty cross was flicked narrowly over by Scarlett.
Curtis then showed some neat footwork to create space to shoot, but his effort was deflected and Scarlett could not meet the loose ball.
Rafferty slid in timely fashion to play a pass back to Josh Griffiths when it looked as though Harrison might get there first.
Cowley freshened things up by making a substitution on 65 minutes, as Curtis was withdrawn for Jacobs.
And another change followed soon after, with a first appearance of the season for Morrell in place of the recently booked Lowery.
Pompey were still looking largely in control, as they tried to find more openings without being too open at the back.
A final double switch in the closing stages saw Reeco Hackett and Jay Mingi on for Dale and lively Scarlett.
And it was fairly comfortable for the Blues late on, with Port Vale not threatening until deep into stoppage-time.
A low shot from substitute Funso Ojo was heading for the net, but Griffiths got down to make the save and ensure the points would be heading back to the south coast.
Port Vale (3-4-1-2): Stevens; Smith, Walker, Hall (Jones 89); Worrall (Massey 62), Ojo, Pett (Small 62), Benning (Hussey 62); Conlon (c); Garritty, Harrison
Booked: Massey, Ojo
Subs not used: Stone, Forrester, Charsley
Pompey (4-4-2): Griffiths; Rafferty, Morrison (Robertson 10), Raggett (c), Ogilvie; Dale (Hackett 76), Pack, Lowery (Morrell 69), Curtis (Jacobs 65); Scarlett (Mingi 76), Bishop
Goals: Scarlett 25
Booked: Lowery
Subs not used: Oluwayemi, Pigott
Referee: Craig Hicks
Attendance: 8,878 (1,685 Pompey fans)
The best video you'll see all weekend 🤩 #Pompey pic.twitter.com/uh6FcVmvaZ
— Portsmouth FC (@Pompey) August 27, 2022