Portsmouth 2 Shrewsbury 0 - Neil Allen's verdict: Blues revel in tactical masterstoke from boss still haunted by Coventry substitution

For some, the August moment lost their endorsement of the manager, signalling the origin of heightening discontent over his Blues reign.

The decision to introduce Christian Burgess off the bench to strengthen a 3-2 lead against the nine-man Sky Blues still pains.

A leveller duly arrived and the backlash threatened Jackett’s job, albeit owners Tornante remaining unruffled from their vantage point outside the Pompey bubble.

Yet while the Blues boss received widespread condemnation for that costly substitution almost six months ago, similarly, he warrants credit for his tactical intervention against Shrewsbury.

If a manager’s reputation can be demolished for perceived poor in-game judgement, it should also be enhanced following a masterstroke adjustment which resulted in victory.

On Saturday, the encounter was drifting, a lifeless first half appeared to be repeating itself after the interval, albeit Pompey’s game having been marginally raised.

Inspiration was required to overcome a Shrews side without a cutting edge, yet armed with three robust central defenders patrolling the back line to great effect.

The conditions were wretched, Storm Dennis gathering pace as the match’s quality understandably wilted, the wind and rain hampering the players’ best intentions.

Then, on 58 minutes, Jackett intervened with a double substitution.

It signalled the removal of Gareth Evans and, perhaps bravest of all, right-back James Bolton, with Ross McCrorie and John Marquis introduced.

Within six minutes, the Blues finally had their breakthrough. In such a tight contest, first blood was always going to be pivotal.

McCrorie hadn’t featured for 13 matches following the recurrence a hamstring injury and then residence on the bench which had seen him exclusively not used.

Previously regarded as Jackett’s preferred option, he offers more attacking thrust than Bolton from the full-back role – if only he can remain available.

Still, the Rangers loanee was handed the opportunity of a first outing in almost two months when he was thrown into the action against the belligerent Shrews.

Then, on 64 minutes, Marcus Harness spun to set the overlapping right-back on his way, who proceeded to create enough space by going on the outside of Omar Beckles to deliver a right-footed cross.

There was Ellis Harrison, coming in off the far post to rise above Ro-Shaun Williams and head home from four yards out, despite the best intentions of a defender positioned on the line.

Delight for Harrison on the occasion of his maiden League One goal since December 7 against Peterborough – and relief for the Fratton faithful to finally witness the end of Shrewsbury’s resistance.

Impressively, McCrorie’s key involvement arrived after barely a touch since his entrance. He can be rightly proud as he steps up the pursuit of Bolton’s place.

With Exeter scheduled to visit on Tuesday night in the semi-final of the Leasing.com Trophy, he can expect another chance to audition for the right-back role.

Yet this was no one-man show from the bench, with Marquis also leaving his mark on proceedings.

The summer arrival from Doncaster found himself out of the starting XI following the midweek defeat at Coventry, one of three changes.

He and close friend and striking rival Harrison have alternated up front during the last four fixtures as Jackett seeks to refresh and reinvigorate his side during this congested period.

Certainly Marquis may feel aggrieved, with six goals in 2020 before the match, with the manager seeming having scrapped the concept of him fulfilling the number 10 role.

For Shrewsbury’s visit, he found himself benched along with fellow starters against Coventry in Ben Close and Ryan Williams.

Instead Gareth Evans was handed a first league appearance since New Year’s Day, with Harness and, of course, Harrison also recalled.

Just like McCrorie, however, Marquis had his chance after introduced in the 58th minute.

There was a glorious early opportunity when Ronan Curtis slipped him in down the left channel, only for keeper Max O’Leary to save his attempt to clip it over him.

Then, on 82 minutes, the ever-willing Harrison produced a challenge on Sean Goss which saw the ball fall to Harness, who pushed a pass to Marquis on his right.

The striker calmly netted with a first-time righted-foot finish for his maiden goal in front of the Fratton end, a moment which prompted a knee slide amid celebrations.

Afterwards, Marquis pointedly mentioned about media references to poaching other people’s goals during the campaign, clearly a genuine source of irritation.

Nonetheless, it was a well-taken strike and number 12 of a season in which he has struck scoring form at precisely the right time, with the Blues heading into the final third of the campaign.

Now double figures also for Harrison, taking his own tally to 10 during a man-of-the-match display demonstrating trademark energy, work-rate and commitment.

In Jackett’s favoured system, nobody in the squad suits the role more and Pompey’s boss must usher such a vital performer through this chaotic spell of fixtures to ensure injury doesn’t intervene.

The selection policy for Exeter will be intriguing, particularly with Joe Gallen insisting the Blues are to field a strong side for the opportunity to return to Wembley.

In the here and now, however, Jackett’s shrewd substitutions enabled Pompey to maintain their top-six presence in League One.

They remain sixth, yet tantalisingly four points off leaders Rotherham with a game in hand as the race for automatic promotion continues to be gridlocked.

Rather galling, the Coventry side which grabbed a late win in the week are now positioned second following inevitable victory at relegation-bound Southend.

As Jackett intimated during the build up to Shrewsbury's visit, this is the time when the table settles and genuine promotion candidates are established.

Pompey are included among that pack, with 19 wins from their last 26 matches in all competitions representing ominous form.

And on Saturday they were indebted to their manager for transforming an unsatisfactory goalless draw into yet another triumph during this encouraging journey.