Konstantinos Karetsas, the teenage talent of Borussia Dortmund, was rushed to hospital on Tuesday after collapsing on the pitch 25 minutes into his UEFA Champions League debut.

The youngster slumped to the turf during the match, prompting immediate concern from medical staff and fellow players. He was taken off the field and transported to hospital for further assessment and treatment.

The incident cast a shadow over what should have been a landmark occasion for Karetsas, who had earned his first start in Europe's premier club competition.