Mainz summer signing Julian Koch is expected to be out for three months after suffering a dislocated shoulder in a friendly.
Koch joined Mainz on a four-year deal after his Borussia Dortmund contract expired and the defender had been hoping for a fresh start after an injury-plagued career.
However, the 22-year-old will now face another stint on the sidelines after suffering the injury in a recent game against amateur side FC Eschborn.
Mainz manager Thomas Tuchel told Allgemeine Zeitung Mainz: "Julian Koch is injured and will be out of action.
"It is a pity as this is a setback for his hopes of a first-team role at our club."