Liverpool's Fabinho ruled out until New Year with ankle injury
The Brazilian, who has this season established himself as a first-choice pick for Jurgen Klopp's Premier League leaders, was substituted after just 18 minutes of the 1-1 draw at Anfield on Wednesday.
Liverpool have announced that the 26-year-old will play no part in their congested run of 10 games between now and the end of December.
A club statement read: "Liverpool can confirm Fabinho suffered ankle ligament damage during the Champions League encounter with Napoli in midweek."
"Further assessment on the injury has discovered Fabinho will be out of action until the New Year," it added.
"The Brazilian will begin a rehabilitation programme with the Reds' medical team at Melwood as he works his way back to full fitness."
Speaking at his pre-match press conference ahead of Saturday's home game against Brighton, Klopp discussed Fabinho's absence.
"Absolute bad news," he said. "We are not 100 percent sure how long it will take but looks sure he will not take part in the Christmas fixtures.
"We have solutions for the position. We are not the only team with injuries. We have to find a solution and that's what we will do."
Adam Lallana, Jordan Henderson and Gini Wijnaldum were mentioned as possible stand-ins, with a reshuffle in the centre likely, but Klopp admitted none represented a perfect like-for-like swap.
"Will the solution be exactly like Fabinho? No, because no-one is like Fabinho," he said.