"Our player Eder Militao underwent successful surgery today for a tear in the proximal biceps femoris tendon in his left leg. The operation was performed by Dr Lasse Lempainen under the supervision of Real Madrid's medical staff. Militão will begin his rehabilitation in the coming days," Real Madrid said in a statement.
Militao felt a twinge in a challenge shortly before halftime in last week's win over Alaves and immediately signalled to be replaced.
It was initially thought the 28-year-old could recover in time for the World Cup, but further tests showed a recurrence of the injury he sustained in December.
Militao has also suffered two serious knee injuries in recent years.