Mohamed Salah has been ruled out of Liverpool's Champions League semifinal match against Barcelona on Tuesday after manager Jurgen Klopp confirmed the forward was concussed during Saturday's Premier League win at Newcastle.
Liverpool must overturn a 3-0 first-leg deficit when they meet at Anfield in order to reach the Champions League final for the second successive season.
But with Roberto Firmino already sidelined with a muscular injury, Klopp revealed on Monday that Salah will also miss the game as a result of the injury sustained when colliding with Newcastle goalkeeper Martin Dubravka at St James' Park over the weekend.
"Both of them are unavailable for tomorrow," Klopp said at his prematch news conference at Anfield.
"Two of the world's best strikers are not available, and we have to score four goals to go through in 90 minutes.
"It doesn't make life easier, but as long as we have 11 players on the pitch, we will try. ... If we can do it, wonderful, and if not, fail in the most beautiful way."
Salah is expected to feature against Wolverhampton Wanderers in Liverpool's final Premier League game of the season on Sunday, but Klopp said the clash with Barcelona was too soon for the 26-year-old.
"It's a concussion, so Mo is not allowed to play," Klopp added. "He feels OK, but it's not good enough from a medical point of view, that's all.
"Together with our supporters this was a long season, and there's a little chance to make it even longer. If not, these are the last two home games of an incredible season. We should celebrate it with a good performance on the pitch and in the stands."
Due to medical regulations relating to concussions, Salah will not be able to train until Saturday, but the Egyptian should therefore be able to play against Wolves on Sunday in what could be a title decider for Klopp's team.
Salah's absence is a major blow for Klopp and Liverpool, who already face a difficult task in scoring at least three goals to salvage the tie on Tuesday.
Without the Premier League's leading goal scorer and Firmino, Klopp could be forced to play both Divock Origi and Daniel Sturridge in attack alongside Sadio Mane.
The Liverpool manager fielded Dutch midfielder Georginio Wijnaldum in his forward three during the 3-0 defeat at the Camp Nou on Wednesday, but Klopp is expected to field a more attack-minded player on Tuesday.
When asked about the injuries, Barcelona striker Luis Suarez said Liverpool still have plenty of capable replacements to threaten the La Liga champs.
"Obviously [Salah and Firmino] are big absences for them," the former Liverpool man said. "But it doesn't change anything in terms of how we approach the game. They have other players to come in with a lot of qualities.
"We have a lot of respect for them. Salah is a very important player, in the top three of the world in the last couple of years. It's a big miss for them, but they have players like Origi, [Xherdan] Shaqiri, Sturridge who can come in. Quality players."
Defender Trent Alexander-Arnold said Liverpool would have to be fearless to have a chance of progressing.
"That's the only way we're going to get a result. If we get caught up in fearing their players, then that's not really going to work," he said.
"We have had decent results this season where we have scored more than three goals, and being at home helps us. There's still that sense of belief, but we know it's going to be hard. But anything is possible, especially at Anfield."