‘Reason we brought him in’: Portsmouth boss salutes Fratton hero in making after Brighton striker’s fiery debut

And the Blues made it clear he wants to see more of the same from the Brighton loanee, after his no-holds-barred showing against Sheffield United.

O’Mahony put in a fearless performance against one of the most physically testing sides in the division in the Blades, in his first outing in a blue shirt.

It was a display which chimed with the home crowd, who immediately warmed to the 19-year-old as he put himself about and played at a high tempo.

O’Mahony seemed harshly penalised for one firm-but-fair challenge in the first half, while the striker dismissed the attentions of powerful defender Harry Souttar in another skirmish.

Mousinho wants the Republic of Ireland under-21 international to embrace his spiky attributes while he’s playing for the Pompey boss.

He said: ‘That’s the reason we brought Mark in.

‘It was because of how good he was in pre-season with Brighton, the promise he’s shown when he was involved in the first team last season and his involvement with Republic of Ireland under-21s.

‘I thought he came in, put himself about and gave two really excellent centre-halves a difficult afternoon. For us it was really pleasing to be able to rely on him for 90 minutes.

‘The two centre-backs, in fact all of the Sheffield United side, are superb - so for Mark to come in and compete with that is really pleasing.

‘You can’t stress how much this is a different level to where he’s been.

‘The Premier League is obviously better than this, but Championship football is just different. It’s a far cry from where he’s been. He carried himself brilliantly, especially with the two weeks out.

‘It’s what we need. We don’t want nice people coming on the football pitch

‘You don’t win football matches by being nice.

‘I want nice, polite, young gentleman off the pitch who treat our fans well and people well - but I want them to be nasty on the pitch.’

Mousinho felt O’Mahony’s performance epitomised the bearpit atmosphere Sheffield United faced, with the Pompey boss clear he wants sides arriving at PO4 this season knowing they can expect a torrid time.

He added: ‘That message got through well at Fratton Park - we’re getting there with that and then this intimidating atmosphere. Sides know when they come to Fratton Park they are in for a tough game. Now I expect more of the same.’