Pompey are mulling over whether to grant Mustapha Dumbuya an instant recall.
The 25-year-old is back after missing the past two matches through international duty with Sierra Leone.
In his absence, Adam Webster and, then, Lee Williamson operated at right-back.
For Michael Appleton, Dumbuya has been one of his most consistent performers this season.
But the Blues boss is still to decide whether he will start against Shrewsbury tomorrow.
Appleton said: ‘Muzzy (Dumbuya) is okay.
‘He trained yesterday and played 90 minutes for Sierra Leone on Saturday.
‘Will he have to fight for his place? Definitely – and I said that to the players yesterday morning.
‘Normally he would come straight back in but, like I say, we’ve had a couple of decent performances from individuals so it gives me a little bit of a selection headache.
‘But it’s one I’m looking forward to.
‘I said we’re in a position, regardless of this 20-player ruling which is difficult, that the small squad we have got now all of a sudden has a little bit of competition for places.
‘Whether it’s in the back four or even the midfield area or front area, we’ve got a few options now, with players who can play in various positions.
‘So, yeah, the team line-up is going to be quite interesting.’