McNulty was forced off towards the end of the first half against Fleetwood Town on Tuesday night after picking up a dead leg during an accidental tangle with visiting 'keeper Chris Neal.
The striker's progress will be checked pre-match to see if he has any chance of featuring.
Fellow forward James Hanson will also be assessed ahead of the Chesterfield away game after taking part in some fitness work at the training ground.
Hanson missed the Fleetwood win and last Saturday's visit to Bolton Wanderers with a calf problem.
Tony McMahon will definitely miss out on the match at the Proact Stadium, with McCall revealing that the defender is expected to miss the next three-to-four weeks with a thigh injury.
McCall said: "Looking back, it was a real whack that Marc (McNulty) took on Tuesday evening.
"He tried to run it off but it tightened up - it was a real sore one.
"He is desperate to be involved but we have to put him down as a major doubt at the moment.
"We'll see how he reacts to treatment in the next twenty-four hours or so.
"It is only a bang so he might still have a chance but I would definitely put him as a doubt at this stage.
"James (Hanson) has done a little bit today (Thursday). It is a bit like with Marc really, we'll see how he is in the (Friday) morning.
"If he comes through it fine, hopefully he can be added to the squad.
"He hasn't done too much work but there is still the possibility he could be involved.
"We reckon that Tony (McMahon) will be out for between three and four weeks. It is quite a deep thigh strain unfortunately."