Sam Hutchinson has been ruled out for at least two months following his latest knee injury.
The midfielder limped off just minutes into the Watford game on Saturday – on his return from a back problem – and now it is expected he will be sidelined until at least Christmas.
Stuart Gray said the only encouraging news from the diagnosis is that it is not the same injury to the knee which has caused Hutchinson major problems in the past.
Also on the injury front, Lewis Buxton is expected to resume full training next week after suffering a knee injury prior to the Watford clash.