Pompey are awaiting to discover the full extent of Amine Linganzi’s injury.
The midfielder was forced off in the second half against Morecambe with a groin strain.
He was replaced for the final 11 minutes by Danny Rose as the Blues were held to a 1-1 draw.
Linganzi has started the last six Pompey matches, impressing alongside Michael Doyle in a holding role.
Now the club’s medical staff are assessing the injury as he battles to be fit for Saturday’s visit of Crewe.
Paul Cook has given the players two days off following their recent busy schedule, which included travelling back from Carlisle by train after the team coach broke down.
And he’s hoping rest and medical assistance can help with Linganzi’s availability.
Cook said: ‘Linganzi came off against Morecambe with a little bit of a groin strain.
‘It is too early to say how it is, he’ll be looked at by our staff over the next few days.’
Linganzi is presently enjoying his longest spell in Pompey’s first-team after wrestling the spot off Danny Rose.
Since recalled against Wycombe, he has produced a number of eye-catching displays, culminating in a maiden Blues goal at Carlisle.
However, he looked tired in the second half of Tuesday night’s Fratton Park encounter with the Shrimps.
Cook later explained there was a groin problem, with Pompey losing their one-goal lead in the towering midfielder’s absence.
The busy period continues with the Blues facing Crewe on Saturday, while then travel to Crawley (March 7) for their game in hand.
Linganzi has made 19 appearances since joining Pompey as a free agent in August following a successful trial.