He suffered an injury to his left knee in an innocuous challenge. Exploratory surgery has revealed a ruptured cruciate ligament, meaning he will be out for between 7 and 9 months, missing the remainder of this season and the start of next.
Phil Brown does have a ready-made replacement in Nathan Doyle, signed during the transfer window, who can play at either right-back or in midfield. He's not eligable to play on Saturday though when City face his former club Derby at Pride Park.
Brown is also without the suspended Ian Ashbee for that game, so John Welsh will make his return to the first team after being laid off with injury.