Borussia Dortmund's teenage star Konstantinos Karetsas was taken to hospital with circulatory problems after slumping to the pitch during a Champions League tie against Villarreal on Tuesday night. The club confirmed the 18-year-old attacker was experiencing "circulation problems."
Karetsas had to be substituted in the 27th minute of the match. Video showed the Greek attacker kicking a ball back to a teammate before sitting down on the pitch in visible discomfort. Dortmund's medical staff entered the field to attend to him, and he was subsequently stretchered off.
"Kosta is doing as well as can be expected given the circumstances, and he is on his way to the hospital for further examinations," a club statement read.
German newspaper Bild reported that Karetsas had missed training on Monday due to fatigue. He joined Dortmund last month from Belgian side Genk for a reported £27 million.
Karetsas's injury occurred during Dortmund's Champions League campaign opener, which they won 3-2 against Villarreal. Serhou Guirassy scored twice for the Bundesliga side in the victory. Ethan Nwaneri came off the bench to replace Karetsas.