John Mousinho is adamant he 'didn't want to' substitute goal hero Mark O'Mahony against Oxford United - but it was a necessity.

The Brighton loanee scored in successive matches when he handed the Blues a 57th-minute lead at Fratton Park on Saturday.

Mousinho's decision frustrated some of the Fratton faithful, who questioned why the goal threat was taken off with the Blues desperate for a first win of the campaign.

Mark O'Mahony celebrates in front of the Fratton End after opening the scoring for Pompey against Oxford United. Picture: Jason Brown/ProSportsImages | Jason Brown/ProSportsImagesThe Blues' head coach agreed - yet with O'Mahony feeling his groin, he felt it wise to remove the 19-year-old from the action.

Mousinho told The News: 'Mark tired towards the end of the game, he slightly felt his groin as well, so we needed to bring him off.

'I didn't want to, but it was something which was flagged at half-time. We kept him on a bit longer than we would probably have liked.

'He has never before had that physical output he's experienced over the past week, so I'm really pleased with him. He took his goal really well, the only disappointing thing for Mark is he didn't score more.

'To come in as a 19-year-old, having never experienced football in the Championship, to play as well as he has done over the past week in those three games is impressive.

'Two goals in three starts is excellent, I have been very, very pleased with his contribution.'

O'Mahony headed home Josh Murphy's left-wing cross in the second half, a goal netted through clever movement from the striker.

He darted across defender Ciaron Brown to steer his header past Jamie Cumming for the first Fratton Park goal from a Pompey player this term.

'Wonderful passing range, Signing of summer, Struggled at times': Neil Allen's Portsmouth player ratings against Oxford UnitedAnd it represented a second in four appearances so far since moving on a season-long loan from the Premier League late in the transfer window.

Mousinho added: 'It was a classy goal he scored.

'We got the ball out wide, it was a really good cross from Murph and Mark got across the front of his man for a really good finish.'