Borussia Dortmund will have to be without Felix Nmecha for "a few weeks" after the Germany midfielder injured knee ligaments, interim coach Mike Tullberg confirmed on Tuesday.
Nmecha went down after a challenge and was subbed out 12 minutes into Saturday's 2-2 home draw with Werder Bremen.
The 24-year-old Manchester City youth product has been one of only a handful of Dortmund players to have escaped criticism amid the club's recent run of poor form.
Dortmund host Shakhtar Donetsk in Wednesday's final Champions League group stage match.
The struggling side have won just one of their past 10 games in all competitions but could still qualify for the top eight with a win, if other results go their way.
"Clearly it's not a simple situation but in every club there's difficult phases and the job is to overcome these challenges," goalkeeper Gregor Kobel told reporters on Tuesday.
"That's what makes a great team... We just need to chalk up some wins and to experience a bit of success again."