Pompey are still assessing Joe Devera over possible knee damage.
The defender was forced off against Exeter just before half-time at the weekend, after appearing to injure his left leg.
Having collapsed to the St James Park turf, physio Sean Duggan immediately indicated for a substitution, with Sonny Bradley replacing him.
Devera managed to hobble off without assistance, while Richie Barker later revealed the problem may not be as serious as initially feared.
However, Pompey are still examining the extent of the problem to the 27-year-old, amid concerns the worst-case scenario could be a sizeable lay-off.
Barker said: ‘Joe got caught from the side and said he heard and felt a major click in his knee.
‘After the game he said he felt a little bit better.
‘I thought initially he just got a kick on his calf, but it turns out in the end it was more than that.
‘It is something we need to look at over the next few days when assessing the damage which may have been caused.’
The injury is unfortunate timing for Devera, who has recently been enjoying the best form of his Pompey career so far.
The former Swindon player had established himself as part of Baker’s preferred central-defensive unit, producing a string of excellent performances in the process.
Previously, he had largely failed to convince the Fratton faithful having been asked to play in a number of positions.
Replacement Bradley was praised by Barker after climbing off the bench to replace his team-mate and is in the frame to continue in his absence.