According to assistant manager Pep Ljinders, Liverpool defender Trent Alexander-Arnold will be sidelined for "probably three weeks" due to a knee injury.
The 25-year-old England international was hurt during Sunday's 2-0 FA Cup third-round victory over Arsenal.
"Trent has hyperextended his knee, resulting in a minor tear in the lateral ligament," said Lijnders.
"He underwent scanning. He will most likely be absent for three weeks. It's a severe blow. He will be greatly missed.
Losing him means we need to discover new dynamics as he was instrumental in our adaptable style of play," Lijnders continued ". He was the one making the difference when we needed it, even during rough patches.
"After getting some rest, he should be able to return to his previous state. Considering that he consistently produced for us from deep and was decisive in every game."
Liverpool, who lead the Premier League by three points, will face Fulham on Wednesday in the first leg of the Carabao Cup semifinal.
In the Premier League, they play Bournemouth on January 21 and Fulham on January 24 for the second leg.
On the weekend of January 27, they play Norwich or Bristol Rovers in the FA Cup fourth round. On January 31, they host Chelsea in the league.
Alexander-Arnold, who was named the team's vice-captain in the summer, has netted two goals for Liverpool this season in 25 outings across all competitions.
Although he is mostly a right-back, he has occasionally succeeded in midfield this season.
Liverpool's Mohamed Salah is playing for Egypt in the Africa Cup of Nations as an international, and Wataru Endo is playing for Japan in the Asia Cup as a midfielder.
As they continue to heal from shoulder ailments, Lijnders stated that left-backs Andy Robertson and Kostas Tsimikas should resume training at the end of the month.
Dominik Szoboszlai, the midfielder, is sidelined due to a hamstring injury, while Virgil van Dijk, the captain, is healthy enough to play Fulham after recovering from illness.