According to manager Alex McLeish the Blues left-back appears to have sustained a knee injury during the 1-0 away win against Watford at the weekend.
"We've lost David Murphy," McLeish has told the Birmingham Mail.
"We haven't got a scan result but it looks like it's his meniscus, so he'll be out for the season.
"He is not going to be able to do anything for the next ten days, so he won't be fit for the last two games."