Karetsas was seen kicking the ball back to his team-mate before sitting down on the pitch in discomfort, with Dortmund medical staff coming onto the pitch to attend to the attacker.

Nach Konstantelias' Kreuzbandriss ist der BVB in Sorge um den zweiten Griechen. Karetsas sinkt beim Champions-League-Auftakt zu Boden und wird in eine Klinik gebracht. Der Club…

Borussia Dortmund’s teenage Greek star Konstantinos Karetsas is being treated at the hospital after slumping to the turf 25 minutes into his Champions League debut against…