Germany international Schmelzer will miss their Bundesliga match against Mainz 05 on Saturday and is unlikely to be fit in time for the Champions League encounter with Marseille next Wednesday.
"He will be doing rehabilitation work until Monday and then can return to team training," the club said on their website. "So playing in Marseille on September 28 is unrealistic."
The German champions drew 1-1 at home to Arsenal in their first Champions League Group F match last week.
Marseille are top of the group after a 1-0 victory at Olympiakos Piraeus.
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