Isak, 26, sustained the injury as he scored Liverpool’s opener, clashing with Tottenham defender Micky van de Ven.
Liverpool have now confirmed that the striker has fractured his fibula and underwent a successful surgery on Monday (December 22).
The club hasn’t confirmed how long Isak is set to be sidelined, but considering the injury, it’s expected he will miss several months.
In a brief club statement, Liverpool said: “The Liverpool striker was injured in a challenge in the process of scoring the opening goal against Tottenham Hotspur and had to be substituted.
“After diagnosis, an operation was completed today on an ankle injury that included a fibula fracture.
“Isak's rehabilitation will now continue at the AXA Training Centre, with no timeframe yet placed on his return.”