Pompey are continuing to assess the fitness of Enda Stevens ahead of the visit to Cambridge United.
The Irishman was substituted in the 59th minute of last weekend’s defeat to Notts County after feeling his hamstring.
Kal Naismith was summoned from the bench to slot in at left-back for the remainder of the 2-1 Fratton Park loss.
The Blues hoped they had caught the problem swiftly enough to prevent it developing into a more long-term concern.
And Stevens has continued to be monitored through the week as Paul Cook weighs-up his options for the forthcoming trip to the Abbey Stadium.
The former Aston Villa man has missed just two of Pompey’s 60 League Two matches since his arrival in the summer of 2015.
No team-mate topped last season’s return of 54 appearances in all competitions for the Blues.
Should he be unavailable for the Cambridge clash, Naismith would again deputise.
Although primarily a winger, the Scot has featured at left-back three times during the campaign, including when Stevens was absent through injury at Crewe.
Youngster Brandon Haunstrup cannot be considered after last week joining Sutton United on an initial month’s loan.
Meanwhile, Gareth Evans has played down injury fears following a second-half knock against Notts County.
The stand-in right-back received lengthy treatment following a collision, but saw out the match.
Evans said: ‘I got kicked on the shin, it was a dead leg again. I seem to get these dead legs at the minute, it’s just part and parcel of being a right-back it seems!’