The midfielder missed Saturday’s Checkatrade Trophy victory over Northampton through a thigh strain.
In his absence, replacement Stuart O’Keefe netted in a 2-0 Fratton Park win to progress the Blues into the last 16 of the beleaguered competition.
Close has featured in Pompey’s side for 13 straight League One outings, but according to Joe Gallen he could be ruled out of the visit to the Valley.
The Blues’ assistant boss said: ‘With Ben, I wouldn’t describe it as a knock, he’s hurt his thigh
‘It’s minimal, but deemed enough for him not to start against Northampton.
‘We have to be careful, we will have to get it right and the decision was precautionary.
‘He’s not a million miles away from maybe being around for Saturday, although that might come too soon.
‘It is something that is difficult to judge.
‘It’s a bit of a thigh strain and it’s pretty minimal, but you have got to get these things right. It is not a bad injury, we will know more this week.
‘All the other lads have small muscle injuries and most of those guys will be back by Charlton – with Ben we will see, I hope so.
‘What we don’t want to do is rush him back, causing a recurrence, then he’s out for 6-8 weeks – when instead you can just wait 3-4 more days. You have to balance it off.’
Kal Naismith, Brett Pitman, Dion Donohue and Oli Hawkins also missed the triumph over the Cobblers through injury.
However, the Blues are hopeful the quartet can return for Saturday’s League One trip to Charlton.
Pompey are currently eighth in the table.
– NEIL ALLEN