The duo were two of a full XI of players missing from Wednesday's Premier League clash with Luton Town, where Klopp was forced to call upon numerous teenagers to fill the bench and handed minutes to Bobby Clark, James McConnell and 18-year-old debutant Jayden Danns.
Both Nunez and Salah had come off worse for wear after the weekend's 4-1 beating of Brentford, in which Diogo Jota and Curtis Jones were forced to depart in the first half with knee and shin issues respectively.
Stefan Bajcetic, Trent Alexander-Arnold, Alisson Becker, Ben Doak, Joel Matip, Thiago Alcantara and Dominik Szoboszlai are also on the Reds' infirm list, and only the latter is thought to be in with a slim chance of returning for the trip to Wembley.
However, speaking to reporters after the 4-1 thrashing of Luton, Klopp admitted that he was still in the dark about the condition of his absentees, but the German was "so happy" to offer Premier League minutes to several academy graduates.
"No. I don't even know if these boys can play again, to be honest. The situation is not great, absolutely not, we don't have to make that now nicer than it is," Klopp said in his post-game press conference.
"I'm so happy that all the kids came on and played, Dannsy [Jayden Danns] said 50 times, 'Thank you, boss!' I'm so happy that I could give him that opportunity, the boys deserve it. But obviously for us there are now a lot of super-important games coming up, and we don't know, we go day by day.
"I cannot say anything about it and I don't know. But after Brentford I had no clue the situation would be like it was now. So, let's see. There's one phrase that stands: as long as we have 11, we will go for it. That's all I can promise."
Not since Leeds United's memorable triumph in October 2022 had Liverpool come out on the losing side of a Premier League home fixture, but Chiedozie Ogbene initially set Luton on their way to emulating the Whites, smacking home at the back post after Tahith Chong's strike was kept out by the underside of Caoimhin Kelleher's legs.
However, whatever choice words Klopp had for his players at half time had the desired effect, as Virgil van Dijk powered home a header from Alexis Mac Allister's corner, before the latter and Cody Gakpo caught Luton napping from a throw-in.
Luis Diaz's composed finish then gave Liverpool some breathing space, before Harvey Elliott sealed an emphatic victory with a fine finish into the top corner, as the Reds opened up a four-point lead over Manchester City at the Premier League summit.
Elliott's strike capped off a record-breaking display for the 20-year-old, who on his 100th appearance for the club became the youngest Premier League player on record to score, have at least five shots, create at least five chances, take at least 10 touches in the opposition box and complete at least 25 passes in the final third in a single game.
"Top performance. And Harvey is a top player; 100 games for Liverpool FC in not the worst period of the club's history, where you cannot afford players who [just] play the position, that's a proper sign," Klopp said on the England Under-21 international's historic night.
"I don't lose patience in these moments, I know that it's a challenge for young boys. When everything is great, they are super talents. When things don't go well, you have to show up. And that's what he's learning more and more. And with 100 games under his belt, we all know he will definitely play another 100, 200, 300 - if you ask him, 500 - for this club."
Following Sunday's EFL Cup showpiece event, Liverpool meet Southampton in next Wednesday's FA Cup fifth-round tie before returning to Premier League action away to Nottingham Forest on March 2.