Brett Pitman looks set to return for Pompey’s trip to Charlton on Saturday.
But Blues boss Kenny Jackett admitted Ben Close, Oli Hawkins, Kal Naismith and Dion Donohue are ‘all looking doubtful.’
Pitman has missed Pompey’s past three games with a hamstring injury.
However, the Blues captain has trained throughout this week and Jackett revealed he is ‘okay.’
The Pompey boss said: ‘Pitman is ahead and has trained this week and is okay.’
Meanwhile, there still remain injury concerns surrounding Close (thigh), Naismith (knee), Hawkins (hamstring) and Donohue (lower back).
The Blues will give the quartet every chance of recovering, but Jackett believes they are unlikely to feature at The Valley.
Jackett added: ‘The likes of Close, Hawkins, Donohue and Naismith, we will give them every chance and every opportunity and we’ll see because it’s still only Thursday.
‘There is sometime before the weekend but they are all looking doubtful.’