But Kenny Jackett’s decision to opt for youth did not backfire as the Blues secured a thoroughly-deserved victory.
In the process, Anton Walkes, Jack Whatmough, Matt Clarke and Brandon Haunstrup claimed a first clean sheet since November.
Some may have feared for the youngsters on the trip to Oldham, particularly with 26-year-old Christian Burgess’ omission.
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But Jackett had no qualms putting his faith in the promising quartet.
He said: ‘It’s sort of ironic that the player with the most experience – Christian Burgess – stepped out and we went with 21 year-olds, with Oldham hardly having a shot.
‘Considering their ages, it is something I thought about.
‘In the end, I didn’t think it was the right day for three at the back – you’ll end up getting pinned back with five and never get out.
‘I thought it was the right day for a back four and also felt Jamal Lowe and Kal Naismith needed to play and Brett Pitman needed to play.
‘So it leant itself towards keeping the three midfield players, putting the three lads up front and than a flat back four.
‘With the decision on the centre-backs, I would rather have it that way than scratching around and moving people out of position.
‘Christian has played 36 games this season, he had an excellent spell from November and December when he was outstanding. He can fight back and if we want to be a successful club it has to be three or four players for two positions.
‘It was quite a young back four, but they dealt with a front pairing (Eoin Doyle and Craig Davies) who had given us a lot of problems earlier in the season.
‘The form of those two was quite a threat, but I thought they were quite quiet on Saturday, so credit to the team.’
Pompey’s reliance on youth since the turn of the year has been largely influenced by injury.
As a consequence, results have fluctuated, but Jackett sees encouraging signs.
He added: ‘They are a good age, not too young.
‘Ben Close has more than 50 games and it’s the right age and right profile.
‘We do need to have more experience, there is no doubt about it, but there’s a core of players that are a good age and have enough games.
‘We hope they are on an upward curve, not over the top coming down.’