Tommy Lee is set to miss out on Saturday's game against Exeter through injury.
The Spireites goalkeeper landed awkwardly on his ankle in training earlier this week, a knock that has put Lee out of contention for the last home game of the season.
"At first, it looked a really bad one and we were fearful that it was a bad one but fortunately for us it's come back looking a lot better," said Paul Cook, speaking to Spireites Player. "Until we get the results of a scan I'm not going to know exactly what it is so I wouldn't like to comment too much."
Lee's consistent run of form was capped off by an outstanding display against Fleetwood Town on Saturday. Cook hails the goalkeeper as one of Chesterfield's brightest talents, the Spireites manager said: "I think he's [Lee] an outstanding goalkeeper, I think he's a great trainer, he's a great lad around the club and certainly going forward, I think he's got a very bright future."
Richard O'Donnell will be called up to the squad for the first time since his loan spell at Stockport, from which he gained plenty of first team experience.
"Certainly Richard [O'Donnell] going out on loan was more to gain first team games rather than sit on the bench," said Cook. "When a lad goes out on loan it doesn't mean its the end of his career, football is about learning."