It is feared Lahm fractured the tarsal bone during the Champions League clash with Fiorentina on Tuesday.
“We hope it’s not too drawn-out, but we’re counting on being without him for the next two or three matches,” reported coach Jürgen Klinsmann.
Lahm said: “I’m assuming I’ll be playing again before the winter break, although we haven’t had the final diagnosis yet.
“It’s a shame when you’re forced to take a break, but it’s not come as a shock. I’ve had much worse.”
