The QPR loanee’s League One presence has been fleeting, no doubt frustratingly since his August arrival in search of regular football.
Yet he has continued to be granted cup appearances – and last night responded with a late Blues winner over Peterborough.
Wheeler’s third goal of the campaign – all outside league action – arrived as the visit of Steve Evans’ side threatened to enter penalties.
With the clock on 85 minutes and the scores goalless, skipper Gareth Evans’ corner was delivered from the left, where it was met by the wide midfielder.
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Wheeler steered a first-time left-footed shot goalwards, smacking against the crossbar on its way into the net for a dramatic winner.
It was enough to settle the encounter, with an unusually-high Fratton Park crowd of 3,313 present for the much-maligned competition.
No doubt those supporters for the earlier-than-usual 7pm kick-off were hopeful of watching progress a little closer towards a Wembley final – and that’s what they got.
Ironically, the decider occurred three minutes after a frantic Pompey penalty area scramble, which saw Christian Burgess twice clear off the line in the same attack.
Nonetheless, Pompey also created opportunities, with Wheeler previously going close in both halves, representing the hosts’ best chances.
But the former Exeter player – and man of the match – made sure five minutes from time to hand the Blues a semi-final place against opposition to be declared when the draw takes place on Friday.
Jackett made seven changes to the side which performed so disappointingly at Oxford United, albeit a standard selection approach to the Checkatrade Trophy.
It meant Craig MacGillivray, David Wheeler, Gareth Evans and Jamal Lowe all retained their places against the Posh.
Elsewhere, Dan Smith was named in his favoured attacking role, asked to perform as the lone striker in the customary 4-2-3-1 formation.
It represented a Fratton Park debut for the teenager, who made his bow in the previous round at Southend as a right-back.
There was a return for Ben Close following an ankle injury, partnering Adam May as the holding midfielders.
While the defence featured Academy youngster Haji Mnoga at right-back, with first-year professional Matt Casey lining-up in the centre of defence with Christian Burgess.
When the match got underway, the Blues were almost gifted the lead on four minutes.
Brandon Haunstrup’s dangerous low cross from the left was nearly touched past his own keeper by Rhys Bennett, the ball whistling by the post for a corner.
Then, in the 12th minute, Evans’ 30-yard right-footed free-kick whistled narrowly over the bar after threatening to find the far top corner.
The deadlock perhaps should have been broken on 22 minutes when a wonderful pass from Burgess picked out the run of Wheeler inside the box.
The forward’s first touch was true, killing it with his right foot, before hooking a left-footed attempt which goalkeeper Conor O’Malley blocked at close range from eight yards.
It was an excellent intervention by the Peterborough man, swiftly off his line to snuff out the threat.
Moments later, Lowe drove in a right-footed shot from outside the box which was nudged wide of the target by the head of Ryan Tafazolli.
The Blues were looking comfortable in defence, while suggesting they could break the stalemate, with Haunstrup the latest to fire a shot from outside the box which sailed wide.
On 35 minutes, however, Peterborough had their best chance of the match so far.
Joe Ward’s cross-cum-shot from the right was tipped onto the bar by MacGillivray and, with Daniel Lafferty following up to net at the far post, Wheeler popped up to slide the ball out for a corner.
It was excellent covering by the QPR loanee, certainly preventing the hosts from falling behind.
With half-time approaching, a sublime first touch from Lee Tomlin put George Cooper through, but MacGillivray was swiftly off his line to gather.
With the scoreline goalless at the break, there were no substitutions when the teams reappeared.
Then another Pompey opening arrived on 51 minutes, again falling to Wheeler.
Haunstrup’s ball into the box wasn’t quite gathered by Smith, yet fell kindly to Wheeler, who lifted a left-footed shot well over the bar from around the penalty spot.
A wonderful piece of skill by Burgess, several times, then left Tomlin embarrassed, prompting the forward to make a late challenge in a fit of pique, although bizarrely escaped a booking.
Jackett made a double substitution on 58 minutes, with Mnoga and Smith replaced by Louis Dennis and Anton Walkes.
Still the sides couldn’t be separated, with Cooper lofting a shot over the bar and then, at the other end, Evans driving an attempt from long range just wide of the post.
On 68 minutes, Lowe committed a foul down Pompey’s left and Cooper’s resulting free-kick was missed by MacGillivray – and a crowded penalty box – on the way for a goal kick.
Steve Evans made his first change on 69 minutes, with Tomlin coming off for Siriki Dembele.
Referee Andy Woolmer had been lenient with his bookings throughout, but he had no choice to make Close his first booking of the game on 74 minutes following a trip on Callum Cooke.
Pompey somehow managed to keep their goal intact on 81 minutes, with Burgess twice clearing off the line in a frantic scramble.
Firstly MacGillivray stopped Cooper’s curling effort, before Toney’s follow-up was blocked.
Then Jason Naismith saw his attempted thwarted by Burgess’ body on the line, with the right-back’s header striking the bar before Burgess then headed it away.
But on 85 minutes it was the hosts who broke the deadlock.
Evans delivered a corner from the left and there was Wheeler to steer a lovely left-footed finish which struck the underside of the bar before entering the net.
Pompey had their lead – with little time remaining to defend it.
Jackett’s men almost doubled their advantage when Evans slipped a pass inside to Dennis who cleverly lost him man before placing a shot just wide of the far post.
The fourth official indicated there was four minutes of time added on to negotiate, and only a save by O’Malley at the feet of Wheeler denied the hosts another.
But this was Pompey’s victory – and a semi-final place secured.