The Greek midfielder suffered a sudden collapse on the field after 23 minutes, with no visible contact with an opponent. He was left lying on the grass for several minutes before being carried off on a stretcher. The medical staff quickly attended to him, and he was unable to continue playing. Ethan Nwaneri replaced him in the match.

Dortmund later released a statement confirming that Karetsas had left the field due to problems with his blood circulation. The club stated that he was on his way to the hospital for further examination.