Bundesliga giants Borussia Dortmund will be without influential Turkish international midfielder Nuri Sahin for two months after he underwent a left knee operation on Wednesday.

The 25-year-old -- who Dortmund bought back from Real Madrid this year -- has been suffering from inflamed tissue in the knee for some time.

He has not played for Dortmund since their 2-0 loss to Bayern Munich in the German Cup final at the beginning of June.