Mohamed Salah has been ruled out of Liverpool's Champions League semifinal 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 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 admitted 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 at the weekend.
"Both of them [Salah and Firmino] 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 concussion, 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 on Tuesday is major blow for Klopp and Liverpool, however, as they attempt to pull off a memorable victory against Barca.
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 last Wednesday, but Klopp is expected to field a more attack-minded player on Tuesday due to the necessity to score at least three goals to salvage the tie.
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."