The 32-year-old suffered the injury in Tuesday night's Carling Cup victory over Luton, where he was playing his first game of the season following a hamstring problem.

Manager Steve Coppell told the club's official website: "Doobs popped his calf, and that usually means something reasonably significant so I can't imagine him being available for another three or four weeks from now.

"It's massively frustrating for him, because he's a really good pro and looks after himself."

Duberry added: "I was hoping to give the manager a selection problem and be in the hat to be involved on Saturday. I'd done all my preparations and put a good shift in but then Lady Luck came and bit me on the backside.

"I just went up for a header, I didn't even jump and my calf popped. Now I just hope it's not too bad."