Pompey secured a third draw in succession after battling from behind in an often scrappy contest at Shrewsbury.
After a forgettable first half, the home side were quickest out of the blocks and took the lead through Rob Street’s header.
But the Blues fought back and Marlon Pack nodded in an equaliser before Tom Flanagan was sent off after collecting a couple of quick bookings.
That was the cue for the visitors to throw everyone forward in search of a winner, but the Shrews held firm.
John Mousinho made three changes from the side held to a draw by Morecambe on home soil on Easter Monday.
Joe Pigott, Reeco Hackett and a fit-again Connor Ogilvie all returned, with Dane Scarlett, Tom Lowery and Denver Hume the men to make way.
Paddy Lane and Michael Jacobs were both considered ready for a spot on the bench after recovering from injuries.
There was not much to excite the crowd in the opening stages, with both sides showing an attacking intent, but neither managing to execute their ambitions in the final third.
The visitors did start to move through the gears as the first half progressed and created a couple of decent openings in quick succession.
Marlon Pack swung in a dangerous corner that Marko Maroši got just about enough on to keep away from the head of Sean Raggett.
Pigott then tried his luck from the edge of the box and saw his shot taking a deflection off Street to divert the ball narrowly off target.
An injury meant a substitution had to be made on 31 minutes – but it was not a player who limped from the field.
Official Tom Nield was the one affected, meaning fourth official Billy Smallwood had to replace him, leading to the Pompey fans unsympathetically chanting: “You’re not fit to referee.”
Shrewsbury had their best chance of the half soon after, courtesy of an audacious 35-yard strike from Taylor Moore that Matt Macey pushed over the bar.
But the Blues then went close themselves when Ryan Tunnicliffe teed-up Pigott, whose effort was spilled by Maroši.
The loose ball ran for Hackett, but Moore bravely flung himself into the path of the forward’s shot to keep the scores level.
Half Time: Shrewsbury 0 Pompey 0
A couple of Shrews throws caused problems when the action restarted, but Chey Dunkley sent the first over, while Killian Phillips then failed to make a connection with the second.
And the hosts did take the lead shortly after, stealing possession in the middle of the pitch and breaking forward quickly.
Elliott Bennett swung in a fine cross from the left that was met by Street’s glancing header, which struck the inside of the post before crossing the line.
It might have got worse for the Blues when Phillips was sent racing through on goal, but Macey was quickly off his line to make the save.
They thought there should have been a chance to level just past the hour mark, when Moore appeared to haul Hackett to the turf inside the box, but Smallwood was not convinced.
Mousinho made a triple change on 65 minutes, with Owen Dale, Hackett and Pigott replaced by Lane, Jacobs and Scarlett.
But Shrewsbury were looking to use up as much time as possible to halt any Pompey rhythm, with keeper Maroši booked for taking too long over a goal-kick.
The visitors were seeing plenty of the ball as the seconds ticked down, but struggling to beach an organised defence.
Jacobs did find a path through after collecting a pass from Bishop and lashing a shot into the side netting.
And an equaliser did arrive moments later and although it was a pretty scrappy affair, the travelling fans could not care less.
Maroši was not able to deal with the corner from Jacobs and Ogilvie headed the ball across goal for PACK to nod home from a couple of yards out.
Flanagan was booked following a scuffle in the immediate aftermath and then fouled Scarlett to earn a second yellow and an early bath.
Pompey committed plenty of bodies forward in their search for a winner and swung in some dangerous deliveries, but Shrewsbury hung on.
Shrewsbury (4-2-3-1): Maroši; Moore, Dunkley, Flanagan, Shipley; Winchester, Leahy (c); Bloxham, Phillips, Bennett; Street (Barlow 90)
Goals: Street 53
Sent off: Flanagan (two yellow cards)
Booked: Street, Bennett, Maroši
Subs not used: Burgoyne, Craig, Owusu, Hutchings, Hearnes
Pompey (4-2-3-1): Macey; Rafferty, Raggett, Robertson (c) (Bernard 90+2), Ogilvie; Tunnicliffe, Pack; Dale (Lane 65), Pigott (Scarlett 65), Hackett (Jacobs 65); Bishop
Goals: Pack 82
Booked: Pack, Robertson, Raggett
Subs not used: Oluwayemi, Towler, Thompson
Referee: Tom Nield
Attendance: 7,020 (1,129 Pompey fans)