Gareth Evans is being assessed following the bang to the head which forced him off at half-time against Crawley.
Approaching the end of the first half of Tuesday night’s Leasing.com Trophy encounter, Jamie Sendles-White clattered into the back of the midfielder during an aerial challenge.
Evans was left barely moving, face down on the Fratton Park turf and requiring lengthy attention from physio Bobby Bacic.
He was able to see out the remainder of the half, while Sendles-White was booked for his challenge.
Yet Pompey’s vice-captain did not appear at the break, replaced by Brett Pitman, with a system change also introduced, restored to a 4-2-3-1.
Pitman would grab the decisive goal on 70 minutes, ensuring a 1-0 victory for Kenny Jackett’s side.
And assistant boss Joe Gallen admitted there were half-time concerns over a ‘groggy’ Evans.
He said: ‘Gareth played very well on the left-hand side, it reminded me of his Checkatrade Trophy final against Sunderland, when he came on and played like he did.
‘But he took a horrible bang to his head against Crawley and wasn't quite right at half-time.
‘It was a bad bang and that’s why he came off. I don’t know if he is concussed, I’m not sure about that, but he will be fine.
‘He is a little bit groggy, it was a hell of a bang, and didn’t move afterwards, which is unlike Gareth.
‘Hopefully he’s okay.’
Evans had been handed a Pompey start on the left-hand side of a 4-4-2 for the visit of League Two Crawley.