Esson went off with a thigh injury in Caley Thistle’s victory over Ross County, which sealed their place in the Clydesdale Bank Premier League top six, while Warren has picked up a knee injury.
Manager Terry Butcher said: “Ryan is going to be out for four to six weeks with a torn thigh muscle. Gary Warren is going to be out for four to six weeks with a [strained] lateral ligament on the outside of his knee.”
Antonio Reguero, who has held talks with Kilmarnock over a summer move, will deputise for Esson when Inverness face Hibernian at Easter Road tomorrow. But former Hibs captain Chris Hogg looks likely to be made to wait for his first-team return, despite appearing for the under-20s following his cruciate ligament injury.
Butcher said: “He is doing well. He has a lot to go in terms of sharpness and timing and instinct – he has been out for a year.
“But Danny Devine is ready to step in. He has played very well for the first team and just signed a new contract.”