In the air duel, Tom Krauss from Nuremberg and Miro Muheim from Hamburger SV crash together.

Krauss immediately sinks to the ground, hit hard, Muheim holds his forehead.

Referee Bastian Dankert immediately waves to the doctors in the DFB Cup game on Tuesday evening.

Krauss is temporarily motionless on the lawn.

Once again, a head hit in football provides a moment of shock and fuels the debate about the risks in aerial combat.

With his head bandaged, Krauss gave the signal on the stretcher shortly after half-time when he was substituted: thumbs up.

"Thank you for all the well-being wishes.

I'm fine, ”wrote the 20-year-old on Wednesday morning on social media, but an exact diagnosis was not known.

"It was a moment of shock for the players who stood around it," said his coach Robert Klauss the previous evening.

The FCN professionals had formed a privacy screen during the scary scene.

Such cases come up again and again in football.

Felix Götze from 1. FC Kaiserslautern suffered a concussion on Monday - and in mid-August the brother of world champion Mario had a hairline crack in his skull and was initially in the intensive care unit.

The debate about the threat posed by such head injuries has long been underway.

The German Society for Neurology in Weimar referred only a few days ago to a study from Scotland, according to which professional footballers have a 3.5 times higher risk of developing a neurodegenerative disease in later life than the general population.

This means that nerve cells perish.

As a consequence, head protection was brought into play.