It could've been worse. According to Spanish COPE Radio reporter Miguel Ángel Díaz, Marcelo will only miss three weeks and Luka Modric could even feature against Borussia Dortmund in the first leg of the tie.
Both players had to leave Saturday's match with injuries. Karim Benzema appeared to have troubles with his ankle as well but assistant coach Aitor Karanka confirmed in press conference that the French striker isn't injured.
Modric could be a very valuable asset for Jose Mourinho in the Signal Iduna Park.