Kevin Richardson has admitted that Ian Miller will struggle to be fit for Saturday's trip to Hereford.
The defender suffered concussion after a nasty head injury at Barnet last week and has not trained all week.
Midfielder Gary Smith and striker Ian Thorpe are both still struggling, but new striker Mor Diop could be set to make his debut.
Richardson said: "For medical reasons, we don't think Ian (Miller) will make this weekend. We've got our fingers crossed, but we have to listen to the medical people.
"Gary (Smith) has been training with the physio this week and has been gradually progressing, and he trained today (Thursday) with the lads. He'll be assessed on Friday.
"Mor (Diop) started very well with us but just picked up a slight thigh strain. He's been back in training but, again, it's whether he has a reaction. If he doesn't I think he'll be involved."
Meanwhile, Stephen Staunton will be hoping to extend defender Moses Barnett's loan with the Quakers after his brief spell at the club expires after the weekend.
Richardson said: "There's a lot of players coming in and out, and we're looking all the time. The manager will look at that situation and he'll make a decision after the weekend."
