Brett Pitman is pencilled in to miss Pompey’s trip to Bristol Rovers.
The striker’s groin problem has yet to allow him to return to training ahead of Saturday’s Memorial Stadium encounter.
Pitman has already missed last weekend’s match at AFC Wimbledon and Tuesday night’s victory over Lincoln through the complaint.
Kenny Jackett continues to stress the injury is ‘minor’ and will not lead to a lengthy stay on the sidelines.
Now it is anticipated he will be absent for a third game, with the visit of Oxford United (November 2) appearing the most likely to mark his comeback.
Jackett said: At this stage, I don’t think Brett will be ready for Saturday.
‘He’s not far away, maybe next week, that would be more realistic.
‘He hasn’t returned to full training, it’s only a minor groin problem, so maybe another week to 10 days as far as I can see.’
Pitman has scored three goals in 11 appearances this term, most recently the winner against Bolton in September.
Before his injury setback against Gillingham, the 31-year-old had re-established himself in Jackett’s starting XI, despite last month having the captaincy removed.
The July 2017 recruit from Ipswich is currently in the final 12 months of a three-year Fratton Park deal which ranks him among the top earners.
Pompey are struggling for goals this season, with 13 from 12 League One fixtures so far, leaving them 16th in the table.
Overall, Pitman has netted 41 times in 94 appearances for the Blues.