Anton Walkes is not expected to play for Pompey again this season.
And Jack Whatmough has also been ruled out of the remaining two matches, with a groin injury.
My physio is doubtful he will play again this seasonKenny Jackett
Walkes hasn’t featured since damaging his hamstring in the 3-3 draw at Rochdale earlier this month.
The loanee today returned to parent club Spurs for the latest assessment on the ongoing issue.
However, Kenny Jackett admits the Blues have little hope of welcoming Walkes back into League One action before the campaign’s end.
It means the 21-year-old will be unable to add to the 12 appearances and one goal of his loan spell.
Jackett said: ‘Anton is progressing, but my physio is doubtful he will play again this season.
‘He certainly won’t be fit on Saturday – and whether he will against Peterborough is doubtful.
‘He was back to Spurs today, they were checking him out.
‘But he will stay with us for the remainder of the season as there is an outside chance of him still playing and an outside chance of us getting into the play-offs.
‘It is the second time he has gone back to Spurs for them to check out his injury and, along with all the loan players, after May 5th he will return to his club.’
Whatmough and Nathan Thompson came off with injuries at half-time in the weekend defeat against Charlton.
Whatmough is sidelined for at least three weeks, while Thompson is a doubt for Bury with a dead leg.
Jackett added: ‘I don’t know whether Nathan will be fit for Saturday, probably not.
‘A dead leg can improve rapidly from Thursday, Friday and Saturday, we will see. If he doesn’t make Bury he will make Peterborough.’