Adam Webster is facing a spell on the sidelines as he waits to find out the extent of his knee injury.
The Pompey defender was forced off in the Johnstone’s Paint Trophy defeat to Northampton, having already replaced the unwell Joe Devera early in the contest.
Webster has already been ruled out of tomorrow’s clash with Mansfield Town and has undergone a scan.
But there are fears he has suffered a ligament injury.
Blues boss Andy Awford said: ‘Adam has seen a specialist and has had a scan.
‘There is some damage there but we don’t know the extent of it yet.
‘He certainly won’t be available for the next couple of weeks.
‘I’m hoping it won’t be too serious. But until we get the results, we won’t know.’
Devera has shaken off his mystery virus and is expected to take his place in defence for tomorrow’s clash with Mansfield.
And on-loan striker Michael Drennan is hoping to declare himself fit after a calf problem.
Awford said: ‘Joe had to come off with a stomach bug but I’m hoping he will be okay.
‘Michael Drennan is the other one and he will be 50-50 for this weekend.
‘He may have a fitness test on Saturday morning.
‘We thought it was cramp when he came off at York but it appears there is a bit of bruising on the muscle and he remembers getting a kick during the game.’
There was more positive news for Awford with the return to training of defender Ben Chorley, although he will not be in contention for the game.
‘Ben Chorley is back in training, so that’s good,’ said the manager.
‘This game will come too soon for him because he has been out for a few weeks, but it will be good to have him back out there on the training pitch.’
Awford was giving little away on his selection for the weekend.
But striker Ryan Taylor reported no ill-effects after a recent groin injury.
‘Ryan Taylor played the whole 90 minutes and didn’t he play well,’ added Awford.
‘I thought he was excellent.
‘He was back to the form from the end of last season and led the line brilliantly.
‘He’s proved to me that he’s fit, confident and raring to go.
‘I left out Pat Agyemang and Miles Storey but it’s not because they have done anything wrong.
‘I wanted Bradley Tarbuck on the bench and Andy Barcham and Ricky Holmes to get some minutes under their belts.
‘A few are pressing for a place.’