Pompey proved they still have plenty of fight left by holding promotion-chasing Derby to a draw at Pride Park.
They went ahead when Colby Bishop headed home his 24th goal of what has been an excellent campaign for the striker.
Substitute James Collins came off the bench to level after the interval, but the Rams could not convert their late pressure into a winner.
John Mousinho made two changes from the side that beat Accrington on home soil the previous week.
Joe Pigott was rewarded for his winning goal against Stanley with a start, while Joe Morrell returned from a four-match ban, as Tom Lowery and Harry Jewitt-White made way.
The sides emerged to a cauldron of noise, with both sets of fans contributing to a cracking atmosphere.
And the hosts soon set about trying to take the lead, causing their opponents plenty of problems in the opening stages.
David McGoldrick was first to threaten after being given space to advance and hit a curling effort from outside the box.
The ball beat Matt Macey and cannoned off the post, hitting the diving keeper on the back and ricocheting wide.
A clearance from Macey was then intercepted and McGoldrick slipped the ball across for former Pompey loanee Nathaniel Mendez-Laing, who fired wastefully past the post.
A Jason Knight header from a corner then bounced into the turf and over the bar, as the one-way traffic continued.
McGoldrick soon went close again, courtesy of another curler from the edge of the box that Macey turned around the post.
But it was the Blues who broke the deadlock against the run of play midway through the first half – much to the delight of the large away following.
It was a lovely pass from Morrell, who lifted the ball right onto the head of BISHOP and he guided it off the inside of the post and across the line.
That stunned the home fans into silence and their side struggled to regain their dominance once the action restarted.
In fact, it might have got even worse for the Rams, with Pompey twice going close to extending their lead before the break.
Paddy Lane and Marlon Pack combined to provide a shooting chance for Pigott, whose drilled effort was turned wide by Joe Wildsmith.
And the keeper then made a superb instinctive save from the resulting corner to keep out Connor Ogilvie’s header.
Half Time: Derby 0 Pompey 1
The visitors made a bright start to the second half, enjoying plenty of possession and frustrating Derby.
It took the promotion-chasing side time to settle and there were a few murmurings of discontent emanating from the stands.
They did win a couple of corners in quick succession just before the hour mark, but both were easily dealt with.
Derby soon threw on attacking players Collins, Tom Barkhuizen and Lewis Dobbin in an attempt to create more openings.
Mousinho also introduced fresh legs of his own on 70 minutes, with the lively Michael Jacobs replaced by Owen Dale.
But it was one of the home side’s substitutes who made a quick impact to level the contest just a few moments later.
A deep free-kick from Conor Hourihane was flicked on by skipper Curtis Davies and the ball was slammed into the net by Collins.
He might have had another goal soon after, but this time could only nod over from another Hourihane set-piece.
Haydon Roberts then flashed a dangerous delivery right across the face of goal, but nobody could capitalise for Derby.
With the visitors looking dangerous, Mousinho moved to shore up his defensive lines, with Clark Robertson and Sean Raggett replacing Ryley Towler and Pigott.
And the Blues saw out the closing stages with relative ease to collect a point and ensure Derby’s push for a play-off place would have to wait until the final day.
Derby (3-4-2-1): Wildsmith; Forsyth (Collins 63), Davies (c), Cashin; Knight, Bird (Smith 76), Hourihane (White 83), Roberts; Sibley (Dobbin 63), Mendez-Laing (Barkhuizen 63); McGoldrick
Goals: Collins 71
Subs not used: McGee, Rooney
Pompey (4-2-3-1): Macey; Rafferty, Bernard, Towler (Robertson 84), Ogilvie; Pack (c), Morrell; Lane, Pigott (Raggett 84), Jacobs (Dale 70); Bishop
Goals: Bishop 24
Booked: Towler, Morrell
Subs not used: Oluwayemi, Thompson, Lowery, Scarlett
Referee: Lee Swabey
Attendance: 31,744 (3,120 Pompey fans)