The planned transfer of forward Serhou Guirassy from VfB Stuttgart to Borussia Dortmund has been delayed due to problems during the medical check.
"During a medical examination of Serhou Guirassy, an injury was discovered and it requires further clarification," Dortmund said on X on Wednesday.
According to media reports, the player has already agreed to a four-year contract with the Champions League runners-up.
The Bild newspaper reported that the issue was an old injury which didn't fully heal. Guirassy suffered the injury while on duty with the Guinea national team. Dortmund are now seeking a second opinion from a specialist.
The transfer can only be finalized after a second medical check, but Bild said that the deal is currently not seriously at risk of falling through.