Cobblers midfielder Alan McCormack is edging closer to a return to full training.
The 35-year-old hasn't been seen by Cobblers supporters since the opening day of the season when he pulled up with a hamstring problem an hour into their 1-0 defeat to Walsall.
The injury wasn't as bad as first feared but due to McCormack's fitness injury record over the past few seasons, Curle has taken extra care to guard against reinjury and ensure he's up to full speed.
Steve Arnold and Reece Hall-Johnson also remain sidelined while defenders Scott Wharton and Joe Martin are both doubts for the visit of Plymouth Argyle this weekend.
"They're all on the road to recovery," said Curle. "They have a timescale been put on them by the physio and we have an inside and an outside date that we try and work to.
"With Alan McCormack, he's coming to the period now where he'll be back to field-based training but there's a protocol that we have to follow because of the fear of re-injury.
"He needs minutes on the training ground doing his extra work and joining in with us and he needs to fulfil the protocol to have the best opportunity to have a long run in the team and that's the same with all the players.
"We have to follow a protocol otherwise you end up with players coming in, coming out, coming in, coming out. If we follow the protocol we give them the best opportunity to stay fit for longer."