After Nick Pope's bizarre red card against Liverpool, Eddie Howe has been left with a goalkeeping crisis ahead of Newcastle's biggest game in decades.
Second-choice goalkeeper Martin Dubravka (34) was on loan from United earlier in the season and is now cup-tied, while the Magpies sent Karl Darlow (32) out on loan to Hull in January, leaving Karius - effectively the club's fourth-choice stopper - as their only recognised senior keeper.
The German is infamous in English football for all the wrong reasons.
He famously cost Liverpool a Champions League title in 2018 after a string of catastrophic errors, notably allowing Karim Benzema (35) to intercept and tap in a simple rollout before palming a tame 30-yard Gareth Bale strike into his own net.
That nightmare performance effectively cost Liverpool the trophy as Real Madrid would go on to win 3-1. The keeper was visibly distraught and seen in tears after the final whistle.
It later transpired that the stopper had suffered a concussion during the match, something that Jurgen Klopp recently, for some reason, was compelled to comment on after his side's recent match on Tyneside.
Speaking after the game against Newcastle in the Premier League, Liverpool manager Klopp was asked his opinion on the prospect of Karius turning out in the League Cup final for Newcastle against Manchester United - a game that really has next to nothing to do with him.
Although it's unavoidable to be posed the question by a reporter in a press conference, it felt disparaging and harsh to highlight the player's one moment in history that has effectively cost him his career at the highest level.
Karius did not play a competitive fixture again for Liverpool after that final, instead finding himself loaned out for two seasons with mixed results at Besiktas in Turkey, prior to another loan move to Union Berlin. He wasn't given a chance by Klopp to rewrite his wrongs in a Liverpool kit.
He has not played a competitive match since featuring in Union's 1-1 draw against Hoffenheim in the Bundesliga in February 2021.
Karius joined Newcastle on a free, short-term contract in September last year but is yet to make an appearance for the north-east club.
But while Liverpool's German coach gave a positive and supportive response, it may have been better to not even dignify the question with a response at all.
After last week's match, Klopp was asked if Karius "had the mentality" to handle another appearance in a final.
"I have no doubt about that," said Klopp. "He's a great goalie, that's why Newcastle signed him."
It seems wrong that a player - any player - should be so concretely defined by one match, no matter how big a game it was, particularly when he arguably shouldn't have been on the pitch at all when the worst happened (which raises the separate question about how well-executed Liverpool's concussion protocols were at the time).
Karius deserves the chance to move on, much like Liverpool fans, his former coaches and the media should allow him to do so. The circus surrounding the keeper going into Sunday's final is remarkably unfair, almost as if the press is already baying for blood and praying for a similarly headline-grabbing shocker of a performance.
The tabloids have no doubt prepped a few pun-driven headlines just in case.
What could have been - and hopefully will be - a story arc of redemption and second chances in the build-up to a huge day for both player and club, has for some reason turned into a chance for old wounds to be re-opened, for bad memories to be revisited, and for a man to be humiliated all over again.
Here's hoping for a solid performance from the former Liverpool man so that his career can finally get back on track.
