Madrid's next match is a tough visit to crosstown rival Atletico Madrid on November 18 after the global break.
Bale's time in Madrid has not been short of success.
The new injury will increase speculation that he could be sold by Real Madrid, who could use his fee to reinvest in new recruits.
The former Tottenham Hotspur man tore a muscle in his calf at the beginning of October, leaving him ineligible to compete in important matches for both club and country; and it's looking like he could miss several more games.
Bale is yet to make an appearance for Real since late September, and the new setback is sure to cast further doubt over his long-term future at the Santiago Bernabeu.
Just 15 months on from carrying his country to the semi-finals of Euro 2016, Bale also had to watch on in agony from the stands as Wales' attempts to qualify for a first World Cup since 1958 fell short last month.
Manchester United boss Jose Mourinho conceded before the start of the season the Red Devils would "wait for him" should Bale ever be discarded by Real.
The 28-year-old Bale was cautiously approaching his return to top form to be ready for the Madrid derby.