The Russian international sustained the injury in a training session on Thursday and is expected to be sidelined for at least one month.
The 35-year-old playmaker will now definitely miss matches against Osasuna, Milan, Atletico Madrid, Espanyol and Barcelona and will be a major doubt for the Galician derby against Deportivo La Coruna on January 3.
The news will come as a huge blow for Miguel Angel Lotina's struggling side who rely heavily on the veteran for attacking creativity.
