Now, he's set for a transfer to the worst team in Europe.
Karius experienced one of the biggest humiliations in football as two jaw-dropping errors from the goalkeeper saw Real Madrid ease to a 3-1 win over his Liverpool team, ending his career at Anfield on the spot.
Two months later Jurgen Klopp signed Alisson Becker for £56million and Liverpool haven't looked back since.
In truth, they've hardly had to, with the Brazilian backstopping them to a Champions League final win the following year and the Premier League the following season.
As for Karius, the German dropped completely off of the radar with loan spells at Besiktas and Union Berlin, only occasionally becoming a meme when he produced more clangers.
The 28-year-old looked to have found a home in the Turkish Super Lig, but after two seasons on loan, he spent the last campaign in Berlin, only featuring five times.
Returning to Merseyside during the summer, Karius has seen his standing drop to fourth-choice shot stopper at best, behind the likes of Adrian and Caoimhin Kelleher.
Unwanted at Liverpool, with his contract up in the summer, Karius may now have one last chance to redeem himself, but the odds will be stacked against him with Europe's worst team interested in his services.
Newly-promoted Bundesliga side Greuther Furth have the lowest points total of any team in Europe's major leagues this season, sitting bottom of the table with four points after 15 games.
With 13 goals scored and 46 conceded, things were far worse for Furth ahead of their first win of the season against Union Berlin last time out, but they've now been dealt a huge obstacle.
Long-term injuries to senior goalkeepers Marius Funk and Sascha Burchert have left the Bundesliga's bottom side with a vacancy in goal, which Karius could fill.
Sporting director Rachid Azzouzi confirmed the club are on the lookout for a new keeper, while manager Stefan Leitl was asked directly about Karius.
"He's undoubtedly a very, very good goalkeeper," Leitl said. "But I'm not involved in names or speculation."
Reports in Germany claim a move could be in the offing, with Karius' last chance at redemption undoubtedly his toughest yet.