
He will undergo further treatment at Bayer 04. A replacement has yet to be called up.
Germany U21 coach Stefan Kuntz said: "It's a purely precautionary measure. In discussion with Jona, our doctors and Bayer Leverkusen we have reached the decision to send the player home for treatment. Of course, it's a pity one of our leading players misses out on the start of the European Championship qualifiers but we do have options in central defence in our squad."

After eight years in the youth set-up at Bayer 04 Leverkusen, Benjamin Adam is leaving the club. The 35-year-old, who most recently coached the Leverkusen U17s, will take charge of the Hansa Rostock U19 team next season.
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As well as internal changes and familiar faces, Bayer 04 are also looking to bring fresh impetus to the coaching staff of the senior youth squads for the 2026/27 campaign. Here is an overview of the U19, U17 and U16 teams.
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Bayer 04 have signed 16-year-old defensive midfielder Kennet Eichhorn from Hertha Berlin. The Germany U17 international is joining the Werkself from the Berlin Bundesliga 2 club on a long-term contract. Eichhorn made 19 appearances for the Hertha Berlin first team last season, scoring two goals.
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Welcome to Leverkusen, Kennet Eichhorn. Bayer 04 have signed the 16-year-old midfielder from Hertha Berlin. Read on to find out more about our new signing.
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