It's so unfortunate that Erik Ten Hag couldn't prove his critics wrong and got sacked so early, I don't know if anyone beats that record but that's the earliest I know of for a manager to get replaced, well from Terzic's early record at Borussia Dortmund when joined them in 2022, I think he'll make a good coach for Leverkusen.

 Edin Terzic first managed Borussia Dortmund in 2022/23 season and helped them finish as runners up with his possession game formation, he's got a good experience in the league and fit to manage the players of Leverkusen,  well from the rest of the options Leverkusen board would bring up, we'll know if Edin would be the perfect replacement for the job.