Borussia Dortmund teenager Konstantinos Karetsas returns to training after Champions League health scare

Borussia Dortmund have said 18-year-old midfielder Konstantinos Karetsas is back in training just over a week after he slumped to the ground in an alarming medical incident on his Champions League debut.

Karetsas passed the ball to a teammate then signaled his distress to the referee before sitting on the grass during Dortmund's 3-2 win over Villarreal on Sept. 8.

He was in tears as he was stretchered off with suspected circulatory problems and was then taken to a hospital, where he stayed for much of last week.

"Konstantinos Karetsas is back in team training as of Wednesday after doing individual sessions at the start of the week," Dortmund said. "It was his first joint session with his teammates after he was taken off with circulatory problems in the game against Villarreal."

Dortmund hasn't specified the nature of any diagnosis for Karetsas, who was signed from Genk for a reported fee of $34.6 million last month, and didn't indicate whether he would be able to play Saturday against Stuttgart in the Bundesliga.

Karetsas plays internationally for Greece but was born in Belgium, where local media have reported that dehydration was suspected as a factor.

"I'm doing really well," he said in a video recorded during a visit to his old club Genk and published Monday on X. "We tested everything and everything is fine. I just need to adjust a bit to the intensity but that will come with time."

"I went out with him but in that moment, he wasn't able to speak," Book said.

- Borussia Dortmund teenager Karetsas hospitalised after slumping to turf in Champions League

Karetsas was able to cheer on his teammates from the stands in Saturday's 3-0 win over Paderborn.

Managing director Lars Ricken said there had been "no warning signs" of any circulatory problems prior to the incident.