Bale was forced off just before the hour mark of Real's 2-1 win over Sporting Lisbon on Tuesday.
Bale was forced off just before the hour mark of Real's 2-1 win over Sporting Lisbon on Tuesday as the European champions secured their place in the last 16 of the Champions League for a record 20th consecutive season.
The Welshman was diagnosed with a "traumatic dislocation of the peroneal tendons in his right ankle".
Real Madrid announced Thursday that it had been decided Bale would undergo an operation in London on Tuesday.
Spanish media reported that he would be out for at least two months.
It means Bale will miss the rest of 2016, the Club World Cup in Japan and probably the first leg of the Champions League last 16 tie.