Germany team doctor Hans-Wilhelm Muller-Wohlfahrt has confirmed that midfielder Sami Khedira will require surgery after tearing the anterior cruciate ligament in his right knee.
The Real Madrid star, 26, was forced off during Germany's 1-1 draw with Italy on Friday.
"Sami has to be treated surgically, we hope that he will be healthy again for the start of World Cup," Muller-Wohlfahrt told reporters.
Germany coach Joachim Low added: "This is a bitter blow for Sami and all of us.
"He is a great player on and off the pitch, he is always thinking positively and this will help and I am optimistic that he will be make it in time for the kickoff of the World Cup.
"We wish him all the best and keep our fingers crossed that the surgery goes well and he can quickly get into rehab."
Khedira has been capped 44 times at senior international level.
