Nicky Wroe opened the scoring from the penalty spot during Tuesday night's 2-0 victory over Oldham at Deepdale but the midfielder came off with a tight calf before full-time.
He will be assessed along with forward Stuart Beavon (shoulder), while Keith Keane will play unless a slot for the hernia surgery he requires can be arranged following a visit to a specialist this week.
Lee Holmes has recovered from a hamstring injury but Grayson is expected to proceed with caution.
"With hamstring injuries, they normally take longer than seven days, so we probably expect him to be missing but you never know with certain players," he told North End's official website.
"If he is any doubt he doesn't play and we leave him for the weekend after."
On his other doubts, Grayson added: "Nicky Wroe came off with his calf a little bit tight, Stuart Beavon's shoulder was a little but sore from the other week when he was concussed and Lee Holmes was out.
"These players, if they don't make it for the weekend we've got others that are desperate for a game."
- Sports & Recreation
- Nicky Wroe