Crofts scored on his Canaries debut in the 3-2 defeat to Watford last Friday but will miss out against the Gills - where he made nearly 200 appearances - after being called up by Wales.
Striker Simeon Jackson is also set to avoid his former side as the Gills believe a "gentleman's agreement" is in place after his big money transfer this summer.
Gills boss Andy Hessenthaler told KentOnline: "I had a chat with Paul Lambert when the deal went through and he's not going to play Simeon."
Manager Paul Lambert has no fresh injury concerns to contend with and will again monitor the fitness of captain Grant Holt. Holt is returning from a thigh injury and came on as a late replacement against Watford but may be rested altogether.
Former Rangers left-back Steven Smith will have to wait for his first start as he is still recovering from an ankle injury while fellow defender Zak Whitbread is a doubt after sustaining a problem in a recent friendly. Midfielder Korey Smith is fine after recovering from an ankle injury.