Konstantinos Karetsas debut UEFA Champions League match ended after 25 minutes when the teenager slumped to the ground in the match against Villarreal on Tuesday night. “Konstantinos Karetsas had to leave the field due to circulatory problems. Kosta is doing well under the circumstances and is on his way to the hospital for further tests,” Dortmund said in a statement.

The incident transpired in the first half when the 18-year-old Greek player passed the ball to a teammate and then signalled to the referee before sitting down. Karetsas was treated laying down then taken away on a stretcher. The score was 0-0 at the time in what was a 3-2 win for Dortmund.

“I hope and I think that everything is OK and I hope that he’s back and fit with us soon,” Dortmund goalkeeper Gregor Kobel told Amazon Prime.

Dortmund c'est terriblement triste leur début de saison, tu avais le potentiel de créé un duo absolument iconique avec Konstantinos Karetsas et Giannis Konstantelias

Résultat, Konstantelias se fait les ligaments croisés au bout de 2 match

Et maintenant c'est au tour de Karetsas…

— JeanBonBeurre #KaneBallonDor (@JeanBonBeurreL) September 8, 2026

Dortmund went ahead through Renato Veiga’s attempted clearance in the 53rd minute before Villarreal levelled with a close-range header in the 66th. Serhou Guirassy restored the lead from Fabio Silva’s pass in the 80th and converted a ​penalty four minutes later after being fouled, before scoring an own goal in added time while ⁠trying to help in defence.

In the other matches, Real Madrid punished two costly Inter Milan mistakes to win their Champions League opener 2-1 on Tuesday, with Kylian Mbappe and Federico Valverde scoring and goalkeeper Thibaut Courtois keeping the visitors at bay at the Santiago Bernabeu.

Erling Haaland struck twice after halftime as Manchester City won 2-0 at Porto, extending coach Enzo Maresca’s winning start following three successive Premier League victories.

Real Betis twice came from behind to beat Lille 3-2 in France, with defender Marc Bartra scoring twice before Troy Parrott grabbed the winner. Lille later had Ethan Mbappe sent off.

Aston Villa held off Club Brugge to win 3-2 in Belgium, helped by two Pau Torres assists, while Razvan Marin’s free kick earned AEK ⁠Athens a ​1-0 home victory over LASK.