Dortmund bosses address Karetsas’ collapse against Villarreal

Borussia Dortmund 's 3-2 opening win over Villarreal in the Champions League on Tuesday was overshadowed by new signing Konstantinos Karetsas being carried off on a stretcher towards the end of the first half.

After the Black and Yellows initially announced that the Greek youngster had to come off due to circulatory problems, managing director for sport Lars Ricken and sporting director Ole Book shed some light on the incident and the player's condition.

"It was a circulatory problem that came completely out of nowhere. There had been no indication that anything was wrong," Ricken said in a post-match interview, admitting he was "quite shocked" by the incident.

Book was there himself and witnessed the incident up close.

"I went off with him, but at that moment he wasn't really able to speak. Obviously, we hope he gets better very, very quickly and that it's nothing serious," he said of the incident, which came "very suddenly".

"He sat down and was then taken to hospital for further examinations, where he still is now. That obviously puts a significant damper on the mood," he added.

Head coach Niko Kovac said he passed on the information that "everything was okay" to the rest of the team because they were "obviously worried too".

Ricken was impressed with how the other players handled the rest of the game given the shock.

"You have to give the team credit; it's not easy at all when a teammate is carried off on a stretcher and you don't know exactly what's wrong with him. You could sense that to some extent among the team and the fans."