Real Madrid's Gareth Bale is set to miss the showdown against arch-rivals Barcelona on December 3 after the club announced on Wednesday that the Wales international had injured his ankle in Tuesday's 2-1 win at Sporting Lisbon in the Champions League.

Bale was forced off just before the hour mark as the European champions secured their place in the last 16 of the Champions League for a record 20th consecutive season.

"After tests carried out on our player Gareth Bale at the Sanitas La Moraleja University Hospital, he has been diagnosed with a traumatic dislocation of the peroneal tendons of his right ankle. His recovery will continue to be assessed," Real said in a statement on Wednesday.

Bale has made 20 appearances for club and country since August, scoring 11 goals.

He signed an extension to his contract at Real in October, keeping him at the Spanish giants until 2022.

Zinedine Zidane's team are four points ahead of Barcelona at the top of La Liga and play Sporting Gijon on Saturday before travelling to the champions for their first El Clasico meeting this season.