Joel Ward is battling to face Leicester.
The south coast derby hero limped out of the Boxing Day defeat to Millwall.
Ward picked up a dead leg and had to be replaced by Aaron Mokoena in the 48th minute.
Michael Appleton’s side went on to lose 1-0 through Dany N’Guessan’s controversial late goal.
Pompey’s medical staff will be able to deliver a clearer verdict on the extent of Ward’s injury tomorrow.
That will be once the problem has settled down.
Appleton remains hopeful the in-form utility man will be declared fit to feature in the New Year’s Eve trip to the Foxes.
But he admitted there remains a chance the 22-year-old could miss out.
Appleton said: ‘Joel is a little bit sore.
‘He got a dead leg against Millwall, although at half time he felt as though he could carry on and we gave him the benefit of the doubt.
‘Then he just looked as though he was struggling chasing the ball in the first few minutes of the second half.
‘I didn’t want to risk him for the weekend so thought it was important to get him off the pitch.
‘Hopefully, he will be okay for Leicester, although we just don’t know yet.
‘Dead legs are one of those where for the first 48 hours you have got to look after it as best you can.
‘We’ve got to see what Joel’s reaction is come tomorrow and Friday.’
Saturday’s trip to big-spending Leicester marks the beginning of three games in nine days for the Blues.
Pompey also face Watford at Fratton Park on Monday, January 2.
They then travel to Chelsea for the third round of the FA Cup on Sunday, January 8.