Real Madrid have confirmed Gareth Bale has successfully undergone an operation on his injured ankle.
A brief club statement revealed Bale went under the knife in London on Tuesday, having suffered damage to the peroneal tendons of his right ankle in Madrid's 2-1 Champions League win at Sporting CP last week.
Reports have suggested that the Wales star could be out for up to four months with the injury.
Bale has netted seven goals in 16 appearances across all competitions this season for Madrid, who top La Liga and face arch-rivals Barcelona on Saturday.
His absence is likely to result in more opportunities for Lucas Vazquez and Marco Asensio, with Madrid dealing with a increasingly lengthy injury list ahead of the latest Clasico.
Toni Kroos and Alvaro Morata are out with respective foot and hamstring problems, while Raphael Varane is back in training but recovering from a sore knee.
Barcelona, too, have a number of absentees, though they have been boosted by the expected return of star midfielder and captain Andres Iniesta.
Luis Enrique is particularly short of numbers in defence, with Samuel Umtiti, Jordi Alba and Jeremy Mathieu all questionable for the match at the Santiago Bernabeu.