Friedrich to undergo back surgery
Friedrich joined the 2009 champions in the close season from relegated Hertha Berlin. The duration of his absence will be determined after surgery, the club said on their website.
"The problem was located in early August after an accident in training," said Friedrich, who was expected to be part of the Germany squad for the Euro 2012 qualifiers against Belgium and Azerbaijan next month.
Germany also play Turkey and Kazakhstan in October.
He was a member of the Germany squad that won third place at the World Cup in South Africa last month.
"We tried to fix the injury by treating it but the continuing problems showed that an operation was unavoidable," said the defender.
"But I will do everything to be back as soon as possible."