The 28-year-old had previously registered with his first touch at Fratton Park after appearing off the bench against Doncaster.
Turning home Denver Hume’s errant right-footed shot, it takes his tally to two in three matches since arriving from Sunderland on transfer deadline day.
'I don't think I realised how much it would mean': ex-Cardiff City and Bristol City man's Portsmouth admission as he chases winning Fratton feeling after homecoming
Former Portsmouth, Sunderland and Millwall ace Aiden O'Brien suffers setback as frustrating start to life at Shrewsbury continues
Danny Cowley makes Portsmouth team selection admission following Cheltenham win - and gives honest assessment of current squad amid early-season promotion hopes
Colby Bishop gives Spurs loanee and England youngster Dane Scarlett raving reviews after making Portsmouth league debut
The role ex-Leicester City, Birmingham City and Charlton Athletic man wants to maintain at Portsmouth after guiding city's young gems at Reading
O’Brien has joined until the end of the season, with both player and club using the second half of the campaign to assess whether there should be a permanent relationship.
And Cowley is already heartened by what he has seen from the ex-Millwall man.
He told The News: ‘I think Aiden carries a real goal threat. He’s a great kid and brought an energy and enthusiasm, he has bounced his way into here.
‘He has come in on a short-term contract, good on him, he has totally backed himself and wanted to be here.
‘This is a brilliant football club and players should really want to come here. I saw that in him and that really encouraged me, he has brought an energy and enthusiasm to the group, which I like.
‘He gets the chance to look at us, we get the chance to look at him, and certainly it’s a relationship which has worked out well so far. I like him.
‘We didn’t want to take him off (against Shrewsbury), but had to make subs and are just learning about Aiden. He hasn’t had too much game time, so we’re just a bit cautious of him.’
O’Brien was selected ahead of Tyler Walker as the Blues made four changes at Shrewsbury.
According to Cowley, they also fielded a 3-4-2-1 system, with the Irishman and Ronan Curtis operating behind George Hirst.
Pompey’s head coach added: ‘We have been critical of our attacking players at times losing the ball too easily, but Aiden looks after the ball, he takes care of it in attacking areas.
‘It’s a balance because we want him to be really positive and direct and give him the freedom in those attacking moments.
‘When we get quick balls to them they absolutely have freedom to make their own decisions.
‘When it’s slower and the opponent gets organised and behind the ball, then we just have to take care of it – and he does it really well.’
A message from the Editor, Mark Waldron
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