The France international was injured in Friday's season-opening 3-1 victory over Hoffenheim, his first Bundesliga match since a previous ligament injury to the same left leg in February that also ruled him out of the World Cup in Russia.
"Coman will require surgery and will be out for several weeks," Bayern said in a statement after the 22-year-old Frenchman was injured shortly before halftime following a rash challenge from Hoffenheim's Nico Schulz.
Fellow winger Serge Gnabry, who along with Coman are regarded as successors to veteran wide men Franck Ribery and Arjen Robben, is also nursing a muscle injury.
Bayern are once again strong favourites for the league title, having won the last six.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
(Reporting by Karolos Grohmann; Editing by John O'Brien)
