The genial striker won’t be pressing the manager for a starting spot against Gillingham nor will he sulk if he’s again earmarked for a place among the substitutes.
In fact, in the unthinkable scenario of Harrison being jettisoned from the match-day squad completely, his attitude that the star & crescent comes first means he’d still cheer on Pompey from the stands.
But, in truth, Harrison would have every right to approach Jackett and ask when he’s going to get a sustained run in the line-up.
It appeared the Welshman would be the Blues’ first-choice striker this season when he arrived from Ipswich in June.
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Despite not scoring in pre-season, Harrison’s work-rate when leading the line garnered plenty of plaudits.
But three days before the League One curtain-raiser at Shrewsbury, the signing of John Marquis meant Harrison was pushed down the pecking order.
The £1m-plus purchase, who scored 67 goals across three seasons for Doncaster, unsurprisingly took up the mantle of spearheading Pompey’s attack.
Marquis has struggled to replicate his previous exploits so far at Fratton Park, however.
He’s bagged just two goals in 13 appearances and failed to fire in his past eight outings.
Marquis’ troubles nadired in being substituted at half-time on his Donny return last Saturday.
It was Harrison who replaced him at the interval, with his task to stretch the Rovers rearguard.
After Pompey were put under incessant pressure in the first half at the Keepmoat, the 25-year-old helped the visitors gain more of a foothold in the game.
More importantly, though, Harrison would see Jackett’s troops take all three points back to the south coast with a stoppage-time header that delivered a 2-1 success.
Any marksman would be proud of the finish. He didn’t panic when James Bolton’s cross came into the box and instead remained composed to get purchase on the ball and loop his effort over keeper Seny Dieng.
It took Harrison’s tally to five in 10 appearances for the season before coming on at Oxford on Tuesday.
For someone who’s never really been regarded as prolific, reaching double figures only twice in his career, the former Wales youth international has displayed his eye for goal.
Four of his five strikes have been with his head, although the ex-Bristol Rovers man’s second goal in the win over Norwich under-21s in the EFL Trophy was as deadly as they come when the ball was at his feet.
Harrison’s started just two of Pompey's nine league games to date and had to remain patient.
He’ll be under consideration to be involved from the outset against Gillingham on Saturday.
But if he still finds himself out of the starting XI, Harrison will remain as upbeat as ever.