Kenny Jackett is facing losing Brett Pitman for Pompey’s next two matches.
The striker has been troubled by a groin problem and is yet to train ahead of Saturday’s visit to AFC Wimbledon.
Although not ruling Pitman out of that fixture, the Blues boss anticipates his former skipper will be out of action.
Jackett also expects to be without the former Bournemouth man for Tuesday evening’s visit of Lincoln.
That leaves the trip to Bristol Rovers (October 26) as a potential comeback date.
Jackett said: ‘Brett will certainly miss Saturday and Tuesday, but I don’t think too much after that.
‘He felt it slightly in the first half against Gillingham, but at half-time wanted to carry on, then gave me the call to be replaced.
‘It seemed to affect him during the game, something which niggled, but it isn’t too bad.
‘He has yet to train, we will see this morning, but I very much doubt he will play Saturday or Tuesday.
‘I am not going to say he is definitely out because he will want me to keep that door open, but I think he is doubtful.
‘He will be determined to try to put himself back in against Wimbledon, which is a good attitude to have, but reality tells me it will be difficult for him to be okay for Saturday and Tuesday.’
Pitman, who has started Pompey’s last three League One fixtures, has struck three goals so far this season.