"Yuri Zhirkov's provisional diagnosis has been confirmed. In the next few days he will undergo treatment at the team's base. At the moment it's impossible to say how long his recovery will take," the team said via their official Twitter account.

The 34-year-old was substituted at half time as his side beat Spain on penalties to reach their first-ever World Cup quarter-finals on Sunday. Russia head coach Stanislav Cherchesov said after the match that Zhirkov was almost certain to play no further part in the World Cup.

Russia will next face Croatia at the Fisht Stadium in Sochi on Sunday morning (AEST).