Naylor, who is currently recovering from a hamstring problem, missed the recent trip to Slovakia but is now closing in on a return.
But Grayson does not want to take any unnecessary risks and he told the club's official website: "These injuries happen and the timescale on his hamstring injury was from the back end of last season to the start of this.
"He's done well to get back running and joining in with training but we have to be careful to make sure there's no setbacks.
"Richard wants to be back as quickly as possible and make sure he is right, and once the physio says he is ready to step into a game situation we will do that."
Jason Crowe, Alan Martin and Lloyd Sam all missed the final game in Slovakia, and Grayson added: "Jason Crowe has trained but Lloyd won't play. If we're in any doubt we won't be risking players because we want to keep as many fit bodies as possible."
Source: PA
Source: PA