Pompey will leave it late before deciding Ben Chorley’s availability for Fleetwood.
The Blues skipper was forced off at half-time against Burton Albion on Tuesday night with an Achilles problem.
Sonny Bradley came off the bench to replace him as the side secured a fourth successive clean sheet.
It is an ongoing injury with Chorley, who is not expected to train today ahead of Saturday’s visit to Graham Alexander’s high-flying side.
The 31-year-old has been a key performer for Pompey since his arrival from Stevenage but at present is regarded a doubt for their next fixture.
Barker said: ‘Ben was sore yesterday morning and didn’t train.
‘He probably won’t train today and we will see where he is.
‘It is all geared around what he thinks. There are no real hard or fast rules or tests we can do to find out whether he is going to be fit.
‘It’s “do you think you are going to be fit?”. He has got to tell us whether it hurts or not and it will be a late call.
‘When you play on a Tuesday night you often get that anyway.
‘Many people wake up the next day and struggle to train because of the amount of damage that gets done to you during a game.
‘So he’s not a lot different to one or two others.’
In his nine games for the Blues, Chorley has helped rack up six clean sheets.
His leadership credentials and combative approach to defending has already made a big impression with the Fratton faithful.
And Barker will be desperate to get him in the side at Fleetwood.
He added: ‘I am concerned Ben had to come off.
‘We knew it was going to get worse and it has done.
‘He’s had to miss a couple of training sessions through it but hopefully we can get him through until the end of the season.
‘In the game he was okay doing everything else apart from doing a good stride.
‘For corners, going from the halfway line to stride up and stride back again for corners was what was causing the issue.
‘Heading, clearing and tackling wasn’t a problem.’