The Blues striker, who has not featured in the first team since making a substitutes appearance in the 3-2 away defeat at Luton back on 14th October, has had his knee washed out after scans revealed cartilage damage.
The injury is not to the knee that had kept the Finland international striker sidelined for more than a year before he joined Blues on a permanent deal from Chelsea at the beginning of last season but it will keep him sidelined for between 8 and 12 weeks, manager Steve Bruce has confirmed.