Portsmouth captain Dejan Stefanovic is to undergo checks to determine whether he has broken a toe.
The 31-year-old defender was forced off after 66 minutes of Saturday's 1-0 home win over Wigan.
He is now a doubt for Saturday's trip to face Charlton at The Valley, and his absence would be a blow to Portsmouth who are the only team from the Premiership or Football League yet to have conceded a goal this season.
Stefanovic has switched from central defence to left-back to accommodate the arrival of Sol Campbell at Fratton Park.
Linvoy Primus has excelled alongside Campbell in the centre, but Stefanovic remains a key member of the defence and manager Harry Redknapp said: 'It will be a blow if Dejan has to miss some games but Linvoy has been fantastic again. He's revelling in playing alongside Sol.'
It has been a welcome boost for Redknapp to see Primus, who turns 33 on Thursday, playing so well in the early weeks of the season.
The former Charlton, Barnet and Reading player is in his seventh year at Portsmouth and managed to survive the cull of players following Redknapp's return to the club last December.
Redknapp said: 'When I took over as manager I honestly thought Linvoy would be looking for his next club but I made him sub in the first game and when we got an injury after 10 minutes Linvoy came on and has not looked back since.'
If the worst fears about Stefanovic are realised, Portsmouth could switch Matt Taylor from the left side of midfield into defence.
Redknapp was also due to assess other options ahead of the trip to south-east London during tonight's reserve match against Aston Villa.
Andy Cole was set for his first appearance since undergoing a knee operation in February while a Manchester City player, and Portuguese midfielder Manuel Fernandes was also earmarked to appear.
New £2.5million Croatian midfielder Nikola Kranjcar and on-loan Cameroon winger Roudolphe Douala may also make their first appearances for the club.