Joe Gallen wants Matt Casey to add aggression to his game as he continues his promising Pompey development.
The centre-back was handed his debut in the 2-1 Checkatrade Trophy victory over Arsenal under-21s on Tuesday night.
Casey impressed alongside Christian Burgess in defence as the Blues marched into the third round of the competition.
The first-year professional made several intelligent clearances, as well as displaying composure on the ball.
Casey’s long-term aim will be to play for Pompey on a regular basis in the future.
Gallen was encouraged by the 19-year-old’s bow against the Gunners.
Now the assistant manager wants Casey to start playing with more ferocity.
‘Matt made a good tackle that was quite aggressive against Arsenal and he’s got to find that,’ Gallen said.
‘Some people don’t get aggressive until they get to 25 or 26.
‘You always think they’re going to be aggressive at 21 but they’re not quite.
‘But Matt has got a presence and he reads the game well.
‘He wins headers, makes blocks and doesn't get too flustered, really.
‘In terms of his development, he has got a long way to go to get into our team. But everyone has got to start somewhere.
‘He's absolutely fine and that’s why he played for us on Tuesday night and why he got a contract.
‘In terms of playing for Portsmouth and getting promotion is a different thing.’
Casey has had two spells out on loan this season.
The 19-year-old was at Southern League premier division south outfit Weymouth before moving to Gosport Borough.
Casey has been a regular at Privett Park when fit, after breaking his collarbone earlier in the campaign.
Gallen stressed how crucial the Botley defender playing regular first-team football will be for his progress – no matter what the level.
He believes coming up against men will force the 19-year-old to be belligerent when on the pitch.
Pompey’s assistant boss added: ‘He’s been out on loan at some clubs, which is important.
‘It’s important to play Saturday afternoon football rather than waiting around for a reserve game.
‘He's got to turn himself into a man as soon as possible.
‘Getting out against men is the one – it doesn’t necessarily matter what level at times.
‘You try to play at the best level you can.
‘But it turns you into a man. You need to be more aggressive and you need to look after yourself.
‘There are points at stake and jobs at stake – he needs to be playing more of that stuff.’