Liverpool duo Philippe Coutinho and Dejan Lovren will miss the crucial upcoming Premier League matches against Arsenal and Manchester United with their respective hamstring injuries.
Both players had to be substituted in the first half of the Reds' 1-0 victory over Stoke City at the Britannia Stadium in the first leg of their League Cup semi-final tie on Tuesday.
As well as missing Friday's FA Cup tie against Exeter City, the pair will also be out of the games with Arsenal and United, while Coutinho is expected to miss additional matches after that.
"Phil is more serious than Dejan and Kolo [Toure], but none of these three players will be available for Friday," said manager Jurgen Klopp.
"Dejan will be available after Manchester United and Phil needs one or maybe two weeks longer.
"We do not know exactly how long, but it is really rare that it is any quicker."
The Premier League fixtures against Arsenal and United at Anfield take place next Wednesday and Sunday respectively, before Liverpool face Norwich City on January 23 and the second leg of the Cup semi three days later in games that Coutinho will also be doubtful for based on Klopp's prognosis.
The former Borussia Dortmund boss added that defender Kolo Toure had only suffered cramp against Stoke, but that would still rule him out of third-round tie at Exeter.
Klopp added: "Kolo was cramp but after three days he is not available. It will not be possible for him to play the next game, but next week will not be a problem.
"We have to take the situation and we go to Exeter, it is a great tournament. I will be there and I will bring a few players with me!
"We have to make decisions for the team and make changes. I do not know who will be available. We will train in two hours and see who will play."