Majstorovic, 34, was training ahead of Sweden's friendly against Croatia in Zagreb when he suffered the left knee injury.
"Daniel will stay in Sweden for the immediate future and will have an operation there soon," said a Celtic statement.
"Celtic's medical team will be in close liaison with the Swedish FA medical team to ensure that Daniel receives the best of care.
"Unfortunately he will be out long-term."
But with Celtic a massive 20 points clear at the top of the table, following second-placed arch-rivals' Rangers 10-point penalty for entering administration, the Hoope should be able to absorb the loss of Majstorovic.
Source: AFP
Source: AFP