Pompey are fearing the worst over goalkeeper Stephen Henderson's fitness.
The loanee was forced off with five minutes left in the draw against Doncaster with a thigh injury.
That led to Kal Naismith taking over as a makeshift keeper, with all three of the Blues' subs used.
Henderson was making just his second appearance of the season after being left in the cold by Nottingham Forest, after a year out with an Achilles problem.
Kenny Jackett confirmed the outlook doesn't look good for the 29-year-old.
The Pompey boss said: 'He says he felt his thigh pop.
'When you do that it's gone. It doesn't look good.
'It looks quite a severe one as it stands at the moment.'