The influential Blues midfielder hobbled off the pitch in 2-0 home win against Middlesbrough on Boxing Day and manager Steve Bruce has confirmed that this latest hamstring injury will keep him sidelined for at least a month.
Dunn's hamstring problems have been identified as being caused by a possible back problem which can be operated on. But the surgery would keep the midfielder sidelined for anything between four and six months and so the club are are reluctant to go down that route mid season.