The fear is Pompey will be without their talisman for the month of October.
Nonetheless, Kenny Jackett is adamant Brett Pitman could no longer be asked to play through the pain barrier.
I could only see us carrying on like this for a number of weeks and then needing doing anywayKenny Jackett
The Blues skipper has been struggling with a knee problem since netting twice against Fleetwood.
That 4-1 win also resulted in him breaking his nose during a gutsy personal display.
A subsequent nose operation had been anticipated – yet 24 hours later Pitman went under the surgeon’s knife to cure his knee agony.
He is now expected to be out of action for up to four weeks, robbing Pompey of their nine-goal striker for potentially five games.
Yet Jackett believes a knee operation for the ex-Bournemouth forward was inevitable – and the club decided to act sooner rather than later.
The manager said: ‘Brett’s had a tough week.
‘He had an operation on Monday and was told when he woke up that he was having an operation on Tuesday as well!
‘I am pleased, particularly with the knee situation. Since Fleetwood it hasn’t quite been right and he’s had some discomfort with it.
‘There’s been a piece of floating bone in his knee and at times it has locked and left him limping.
‘For maybe a week to 10 days it hasn’t gone away and it needed to be brought to a head. We had to conclude it.
‘The medical people said it was best them going in, observing and then taking it out, making sure there was no other damage inside.
‘I thought it was the right decision as well. It was some relief for myself when it was actually done because I couldn’t necessarily see it going away.
‘Now it gives Brett a chance to clear up both areas (his nose and knee) and I am pleased it has come to a conclusion.
‘I could only see us carrying on like this for a number of weeks and then it needing doing anyway.
‘The estimation is he will be out for anything between two and four weeks, while the medical people are pleased there were no complications or anything unexpected.
‘How quickly he comes back – we will just have to see.’
Pitman has scored nine goals in 11 League One fixtures since his summer arrival.
This week has also seen fellow striker Conor Chaplin sidelined following a recurrence of his hamstring problem.