Although the 35 year old is back in training after undergoing a double hernia operation over the summer, he is now struggling with a hip injury.
"Alan is training but kicking is the problem," explained Jefferies. "He had an injection but it's not worked so we're waiting to see if anything else can be done.
"If not he may need an operation which would keep him out for three-and-a-half months and we'd have to sign a keeper for the short-term.
"It's a blow because we are already waiting for James Fowler to go in for a hernia op."