A stretcher was carried onto the pitch, but Isak was eventually helped off the field by Liverpool’s medical staff.
Liverpool said in a statement: “Following diagnosis, surgery on his ankle injury, which included a fractured fibula, was completed today (Monday).
“Isak’s rehabilitation will continue at the AXA Training Center, but a return date has not yet been determined.”
Isak has played 16 games in all competitions for Liverpool, scoring just three goals.
Carragher: “Semenyo could be a good way to avoid injury to Isak”
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Analysis: Slot attack options are reduced
Rich Morgan of Sky Sports:
Isak missed four games in late October and early November with a groin injury, and was sent off at half-time of the Champions League win over Eintracht Frankfurt.
He has started five of the nine matches since his return, but any absence, even for an extended period, would be a blow, with Mohamed Salah set to feature in the Africa Cup of Nations and Kodi Gakpo not expected to be ready to return until early in the new year following a muscular injury.
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Free to watch: Premier League highlights of Tottenham Hotspur vs. Liverpool
This leaves Hugo Ekitike, who has scored five goals in the last four games, and Federico Chiesa, who has rarely been used, as the only senior forwards in the slot.
Unlike Isak, Ekitike has only really hit the ground running since his £79m move to Anfield from Frankfurt last summer and has scored 11 goals in 24 games in all competitions so far this season, including eight in the Premier League.
And with Isak sidelined through injury, the 23-year-old has a chance to stake his claim for the championship’s first-choice number nine spot in a crucial game.
Liverpool will face Wolves, Leeds, Fulham and leaders Arsenal over the next two-and-a-half weeks to shape their aim of finishing in the top four.
Meanwhile, the Reds begin their FA Cup campaign at home to Barnsley on January 12, and have two crucial Champions League games next month, at Marseille (January 21) and at home to Qarabag (January 28).
Liverpool’s next 5 games
27 December – Wolves (H) – Premier League 1 January – Leeds (H) – 4 Premier League January – Fulham (A) – 8 Premier League January – Arsenal (A) – 12 Premier League January – Barnsley (H) – FA Cup
