England international midfielder Owen Hargreaves will be out for at least six weeks after breaking his left leg.
Hargreaves made his mark in England's World Cup side
The 25-year-old came off after 24 minutes of Bayern Munich's 2-1 league defeat by Arminia Bielefeld after colliding with opponent Thorben Marx.
He will miss England's Euro 2008 qualifying matches against Macedonia and Croatia in October.
"I need to wear a plaster for three weeks then we will have to see how it goes," Hargreaves said on his website.
Bayern Munich said Hargreaves could return in early November if his recovery went to plan.
Hargreaves added: "After we got back to Munich, we drove to see Dr Muller-Wohlfahrt, I got X-rayed and it was revealed the left fibula was broken.
"That's the way it is in football. Sometimes you are flying high and all of a sudden you are down again."
The midfielder, who has been a transfer target for Manchester United, cemented his place in the England team at the World Cup in Germany this summer.
Many questioned the then England boss Sven-Goran Eriksson's decision to take Hargreaves to the tournament, let alone start with the Canadian-born player.
But Hargreaves won over the doubters with a stellar performance in the quarter-final defeat by Portugal and has continued to shine in the three matches under new coach Steve McClaren.
He has taken on David Beckham's number seven shirt in national colours as well as being targeted by the Real Madrid star's former boss at Old Trafford, Sir Alex Ferguson.
However, Bundesliga champions Bayern blocked a potential move to United after losing Michael Ballack to Chelsea in the transfer window.
Hargreaves was not selected by Bayern boss Felix Magath as speculation over his future intensified.
However, since transfer deadline day on 31 August, he has reclaimed a starting place in the midfield alongside summer recruit Mark van Bommel.
A first defeat of the season means Bayern have slipped back to third in the Bundesliga.
They were leading when Hargreaves went off following Van Bommel's early strike but Bielefeld bounced back and grabbed all three points with a late winner from Jonas Kamper.