Damien McCrory will see out the remainder of his loan with Pompey, despite facing a month on the sidelines.
The left-back has made only three appearances since his deadline-day arrival from Burton.
A twisted knee forced him off against Fleetwood for what was initially anticipated to be a short absence.
However, he today underwent knee surgery after cartilage damage was detected.
Kenny Jackett has already lost Tareiq Holmes-Dennis for the season – now fellow full-back McCrory will miss the month of October.
But the Blues boss is pencilling the 27-year-old in to feature again before his loan spell is up for renewal in January.
He said: ‘I think Damien will stay here because he’s contracted to us until January.
‘Besides, basically he will be out for October but still has November and December. He should be okay.
‘He went for a scan and saw a specialist and the assessment was he had some cartilage damage and they needed to go in and tidy up.
‘There have been quite a few operations and they have mainly come across the back line.
‘It is what it is, the squad and the club have to adjust and adapt.’