The Welshman picked up the knock during Real Madrid's 2-1 win over Sporting Lisbon in the Champions League on Tuesday night
Real Madrid face into their first league El Clásico of the season without one of their key players after Gareth Bale picked up an ankle injury on Tuesday night in the Champions League.
Zinedine Zidane's side needed a late Karim Benzema goal to keep them within touching distance of Borussia Dortmund at the top of Group F and their victory means they will now face the Germans in the last round of group games to decide who finishes in top spot.
The result, however, came at a price as Bale was forced off the pitch after injuring ankle tendons against their Portuguese counterparts.
The injury, coming as a result of a chellenge from Sporting defender Sebastian Coates, saw him replaced by Marco Asensio.
It appears the 26-year old suffered a dislocated ankle and will be sidelined for as many as four weeks.
"After tests carried out on our player Gareth Bale he has been diagnosed with a traumatic dislocation of the peroneal tendons of his right ankle," a club statement read. "His recovery will continue to be assessed."
He will now miss their tie against Barcelona on December 3rd and will also likely miss their clash with Dortmund less than a week later.
Real Madrid currently lead La Liga on 30 points, four clear of Barcelona and six clear of Sevilla.