Craig MacGillivray is pencilled in for a Pompey return against his former club.
The goalkeeper was ruled out of Tuesday night’s visit of Southend after feeling his quad during training on Monday.
Following a scan deemed ‘inconclusive’, it was decided not to risk the Scot, with Alex Bass instead promoted into Kenny Jackett’s first-team.
The Blues subsequently beat Sol Campbell’s side 4-1 to rise to 13th in League One.
Pompey’s next fixture is Monday night’s FA Cup clash at non-league Harrogate Town, a club MacGillivray once represented.
And Pompey are hopeful the 26-year-old will be available.
Joe Gallen said: ‘On Monday morning, Craig went to take a few goal-kicks and on the first one felt his quad.
‘On the scan that afternoon it was a slightly inconclusive result, it didn't quite show there is a clear tear in there, but either way he was a bit too risky to play against Southend.
‘If he kicked the ball out and ruptured his quad, it could be six weeks.
‘Craig has never been injured, he said that to me, I thought he was joking but he wasn’t! I explained how it works with these injuries and you need a certain amount of time for them to heal.
‘I wouldn’t be writing Craig out for the Harrogate game because it’s not conclusive, we don’t quite know the damage is in there.
‘If we look after it, I don’t think Craig is going to be out for too long. Although I think Ross (McCrorie) could be out for a number of weeks.’