Real Madrid midfielder picked up an injury during a friendly match against Italy on Friday.
The 26 year old suffered a torn anterior cruciate ligament after colliding with the Azzurri star Andrea Pirlo and afterwards he was forced to leave the pitch on the 67th minute.
Doctors have confirmed that the German star has suffered a torn ACL.
Reports are saying that the German midfielder could be out for the whole 2013-2014 season, but Germany remain hopeful that he will be back before the start of the World Cup next year in June.
Real Madrid have to play whole season without him.
Germany doctor Hans-Wilhelm Muller-Wohlfahrt told the official Deutscher Fußball-Bund (DFB) website that Sami will have to undergo an operation. They hope that he will be fit before the start of the World Cup.
The exact details have not been given by the doctors regarding his return, but reports are suggesting that he will be out for at least six months.
Germany coach Joachim Low said that this is a huge blow for Sami and the rest of the team. He is a hard working player, the real fighter, and always remains hopeful.
Joachim is confident that Khedira will be fit to play in the World Cup.