Pompey fear Gabor Gyepes could be out for the remainder of the festive schedule.
The defender hurt his hamstring in the Boxing Day defeat to Crawley and had to be substituted.
Encouragingly, at this early stage the injury does not appear to be a severe one.
However, Guy Whittingham has been forced to rule him out of tomorrow’s visit of Yeovil.
With the fixtures coming thick and fast at this time of year, Gyepes also remains a serious doubt for Swindon (January 1) and Walsall (January 4).
In addition, the 31-year-old’s contract is up on January 5 and has indicated he wants a long-term deal at a club.
For the Glovers match, Lubomir Michalik will deputise at centre-half in a defence also missing the suspended Jon Harley.
Pompey are also waiting for the green light to add Jed Wallace to their official match-day squad.
The Blues are hoping Gyepes’ absence will not be for long.
Yet it remains realistic he will miss the next few games at the very least.
Whittingham said: ‘Gabor’s injury is bad enough that he won’t be featuring on Saturday.
‘After that it depends on how quickly it settles down.
‘He felt it and then came off almost straight away (against Crawley).
‘It came about when he got the corner. I’m not quite sure whether it was a step over he did that nicked it, but he got the corner and that movement off the mark just pulled his hamstring a little bit.
‘The good thing was it wasn’t in a big stride out so it hasn’t been a big tear. It wasn’t a 40-50 yard run where you are stretching your legs and it goes straight away.’