Kenny Jackett is hopeful Tom Naylor can maintain his crucial presence in Pompey’s league campaign.
The key performer was absent from Sunday’s last-gasp FA Cup victory at Rochdale.
A groin problem sidelined the combative midfielder from the Spotland fixture, with Ben Close replacing him in the 1-0 triumph.
The Blues are now eyeing Naylor’s return against Southend at Fratton Park next weekend.
The summer recruit, who felt the injury during training, was not risked at Rochdale and will also sit out Tuesday evening’s Checkatrade Trophy clash with Arsenal under-21s.
But Jackett is optimistic the first-team regular will be available for the table-toppers’ fixture with Southend (December 8).
Pompey’s boss said: ‘Tom felt his groin and I didn’t think it was worth risking.
‘Hopefully we can make sure that by next weekend against Southend he is back.
‘He felt it Thursday, Friday and Saturday in training and it wouldn’t shake off quickly enough, unfortunately.
‘We thought it might have gone, but it didn’t – and I felt it wasn’t worth the risk of provoking it further.
‘He would have played if he had been okay, but we took the decision not to risk him.
‘I hope he is fit by Saturday. I don’t think Tuesday night, but I do think he has a chance on Saturday.’
Naylor has made 21 appearances and scored twice since his summer arrival.
He has missed just one match in a League One season which has seen the Blues occupy top spot for more than two months.