Real Madrid have confirmed that defender Marcelo is suffering from traumatic athritis in his left knee.
The Brazil international reportedly picked up a knock in Friday's training session ahead of Saturday's visit of Real Sociedad and has now been diagnosed with traumatic arthritis.
And the 25-year-old, who missed five games in September because of a hamstring problem, now faces another spell on the sidelines after being excluded from Real's squad for the game against Sociedad.
No timetable has been set for Marcelo's return, leaving manager Carlo Ancelotti short of options at left-back after Fabio Coentrao sustained an ankle injury in the 3-2 win over Rayo Vallecano last weekend.
A statement on Real's official website read: "Following examinations and scans carried out today Marcelo at Sanitas-La Moraleja hospital, he has been diagnosed with traumatic arthritis in the left knee."
Ancelotti's men sit six points adrift of league leaders Barcelona ahead of the clash with Sociedad, and the Italian is expecting the Basque outfit to present a difficult challenge.
"Real Sociedad is a good team with a good attitude," he said.
"They're very dynamic and have fast players. It won’t be an easy match. They already proved against Manchester United that they can play major games and it's a really good test for us because we need to play well and with intensity."comments