The Pompey striker returns to his former club this weekend on a hot streak as one of the division’s in-form strikers.
Hirst will sign off for the season looking to finish an excellent second half to the season - bagging all of his 14 goals since November.
The Leicester City loanee will expect a torrent of abuse from Owls fans, after he left the club for Leicester in acrimonious fashion in 2019 after a contract dispute.
That was the case at Fratton Park in December’s 0-0 draw between the sides, with the intensity of vitriol expected to be ramped up as Darren Moore’s men chase a play-off spot in front of a sellout crowd.
But Cowley has full confidence Hirst will thrive in such an environment.
He said: ‘He’ll probably get a lot more flak this weekend, I would anticipate!
‘But it’s a game he’s looking forward to and he’s in a really good moment.
‘He played really well against them earlier this season. I’m sure he’s going to be focussed on playing well against them on Saturday.’
After a campaign in which he failed to score while on loan at Rotherham, Hirst’s stock has risen with only two players scoring more goals in League One this calendar year.
Cowley added: ‘I just think when we recruited George, we could see his potential.
‘He’d just had a really good year at Rotherham.
‘He then picked up the injury at the back end of the season, so it took him a little bit of time to get him up to full speed.
‘As soon as we were able to do that we’ve seen him grow, develop and become the forward we thought he was capable of being.’