Pompey are awaiting the results of a scan on Simon Ferry following his latest setback.
The midfielder limped off after 50 minutes of Saturday’s 1-1 draw with Mansfield.
The Blues’ skipper has been troubled by a hamstring injury this season on three separate occasions.
It has raised concerns the problem could potentially emanate from his back, causing the injury in his hamstring.
As a result, Ferry underwent a scan on his back on Monday, with the Blues medical staff now awaiting the outcome before deciding their next move.
Regardless, the ex-Swindon schemer is a doubt for the weekend trip to Morecambe – just two games into his comeback from his last hamstring complaint.
That could open the door for a recall for Frenchman Thery Racon, having impressed after replacing Ferry against the Stags.
Meanwhile, Richie Barker has insisted Ricky Holmes is progressing after being sidelined.
The winger sustained a head injury in the New Year’s Day defeat at Southend.
The Blues are monitoring the situation and, as a result, he has yet to return to full training.
It means Holmes has missed the past two matches and only has an outside chance of returning to the squad for Pompey’s first-ever visit to the Globe Arena.
Barker said: ‘He has done some training, so we need to see how he reacts as we go on.
‘It’s his concussion from Southend and, obviously, a fairly serious thing and has to be graded back.
‘It’s not just having a kick on his ankle.
‘It’s a serious thing and has to be graded back into training.
‘I know he did go to hospital when it happened. He may have stayed in for the night, but that was the maximum.’
Definitely missing for the trip to Lancashire is new signing Ben Chorley, who is banned.
The central defender is sitting out the final game of a three-match suspension collected following his sending off while representing former club Stevenage.
Chorley was given a straight red for violent conduct at Oldham earlier this month.