Jack Whatmough is unlikely to feature for Pompey again this season.
The defender failed to reappear for the second half of Saturday’s defeat to Charlton after injuring his groin.
He had started eight games in succession, but is now expected to miss the clashes with Bury and Peterborough.
Nathan Thompson also went off against the Addicks with a leg problem, although he could still play a part this term.
Blues boss Kenny Jackett said: “Jack’s pulled his groin and should be out for a few weeks, so I don’t think he’ll play again this season.
“It’s disappointing for us and for him, but the positive thing is it’s not his knee and something he can overcome.
“Christian Burgess had lost his place to Jack, but now he’s got a chance and it’s up to him to finish the season off strongly.
"It’s disappointing for us and for him, but the positive thing is it’s not his knee."
“We’ve set him targets of where he needs to improve in order to become a really dominant centre-half and I believe he can do that.
“Nathan’s got a dead leg which is a bit more straightforward, but he probably won’t be back for this weekend’s game.
“Anton Walkes is also progressing, although my physio is doubtful that he will play again for us this season.”
Pompey now look unlikely to make the League One play-offs, although Jackett believes there are still positives to take.
He said: “There have been a lot of good things about this season and the club is in a very strong position.
“It’s in a stable position off the field, while on it we have some quality players with a number of years ahead of them.
“We do need more, though, and will look to complement those guys by recruiting well over the summer.”