Pompey finally saw the light at Harrogate Town to book their place in the second round of the Emirates FA Cup.
The tie was delayed for 55 minutes because of a power failure at the non-league side’s Wetherby Road home.
And they shocked their higher-ranked opponents by racing into an early lead, courtesy of Mark Beck’s header.
But Brandon Haunstrup impressive drew the Blues level and Ronan Curtis hit an even better winner before the break.
It was the visitors’ first victory on an artificial pitch and the result secured a home clash with Altrincham in the next stage of the competition.
Kenny Jackett made three changes from the side that comfortably beat Southend in the league six days earlier.
Craig MacGillivray recovered from a thigh problem to replace Alex Bass between the sticks, while the injured Ellis Harrison and Ross McCrorie made way for Haunstrup and Gareth Evans.
The teams finally emerged following two delays – the second, thankfully, a lot briefer than the first – and observed a minute’s silence to mark Armistice Day.
But Pompey might have been wishing that the game had been called off after falling behind with just seven minutes on the clock.
The hosts had already enjoyed a couple of forays forward before taking the lead following a free-kick from deep on the left.
George Smith’s delivery was not dealt with and Jack Muldoon headed the ball across the face of goal for Beck to nod home.
The Blues did look dangerous at the other end, although seemed to struggle with the strong wind and artificial surface.
John Marquis was not quite able to collect Haunstrup's threaded pass, while Ryan Williams’ cross was cleared before it could reach Evans.
But a leveller did arrive on 17 minutes and it was a fine strike from HAUNSTRUP to open his Pompey account on his 50th appearance for the club.
The left-footed right-back raced in from the flank and collected a pass from Williams before curling a shot past James Belshaw from the edge of the box.
Josh Falkingham tried to hit back immediately, but the Town skipper’s strike hit team-mate Beck on its path to goal.
The 3G surface had been much talked about before the tie and more questions were posed when three players went off injured before the break.
Two of them belonged to the visitors, with skipper Tom Naylor and later Sean Raggett limping from the field and replaced by Anton Walkes and Paul Downing respectively.
There were chances at both ends in between those changes, with Muldoon crashing a shot into the side netting.
A fierce low effort from Ben Close was then smartly saved by Belshaw, who had to get down quickly to beat the ball away.
Harrogate caused problems with a corner on 36 minutes, but MacGillivray – appearing against his former club – was able to punch clear.
And the Blues then took the lead before the break – and it was a goal that was certainly worth waiting for.
Williams laid the ball off for CURTIS, who hit a rocket from 30 yards that dipped beautifully into the net.
Half Time: Harrogate Town 1 Pompey 2
Curtis put in a shift at the opposite end of the pitch once the action restarted, getting back into his own box to halt a dangerous Harrogate attack.
Williams came close to scoring his first Pompey goal soon after, with an audacious attempt from wide on the right that Belshaw managed to palm away.
The loose ball eventually fell to Walkes, whose own effort was not quite so impressive, with the ball flying out of the ground.
It was generally a much calmer occasion, however, with little of the frantic action seen before the interval.
But the Blues almost extended their lead just past the hour mark, as Belshaw twice denied Marquis from point-blank range after the striker had been picked out at the back post by Evans.
George Thomson, just moments after coming off the bench, then hit a fierce shot inches past the post for Harrogate.
He subsequently sent a corner into the Blues box, where Beck’s downward header was comfortably held by MacGillivray.
And the same duo combined again from a set-piece soon after, with Beck this time depositing the ball onto the roof of the net.
Lee Brown went close with a cross-shot that could neither find the bottom corner or Williams at the far post.
But Harrogate were still applying plenty of pressure and MacGillivray was called into action to deal with Alex Bradley’s effort.
They saw plenty of the ball in the closing stages, but the Blues were able to see things out to secure progress.
Harrogate Town (4-4-2): Belshaw; Fallowfield, W.Smith, Hall, G.Smith; Kiernan (Bradley 70), Falkingham (c), Burrell (Emmett 32), Diamond (Thomson 63); Muldoon, Beck
Goals: Beck 7
Subs not used: Cracknell, Taylor, Brown, Jones
Pompey (4-2-3-1): MacGillivray; Haunstrup, Burgess, Raggett (Downing 31), Brown; Naylor (c) (Walkes 24), Close; Williams, Evans, Curtis; Marquis
Goals: Haunstrup 17, Curtis 41
Subs not used: Bass, Bolton, Cannon, Harness, Pitman
Referee: Anthony Backhouse
Attendance: 3,408 (616 Pompey fans)