A brain injury charity has called for a UEFA investigation after Fabian Schar was cleared to play on after being knocked out.
The Newcastle United defender lost consciousness after clashing heads with an opponent during Switzerland's 2-0 win over Georgia.
Schar has said he was "knocked out for a few seconds" in Tiblisi.
Georgia's Jano Ananidze tried to stop the 27-year-old's tongue from blocking his airway as he lay prone on the ground.
Schar had around five minutes of treatment from medical staff before completing the duration of the game.
A statement from Headway on Monday said: "The charity has demanded UEFA launches an investigation into the circumstances that resulted in Swiss player Fabian Schar being cleared to continue playing in a match against Georgia – just minutes after being knocked unconscious and needing emergency help from a member of the opposition."
Headway chief executive Peter McCabe added: "What is it going to take to make football take concussion seriously?"
Schar was quoted by Swiss newspaper Blick on Saturday as saying after the match: "I cannot remember anything.
"I was knocked out for a few seconds. My skull is still buzzing. I also have neck pain and a bump on the forehead. But it was worth it."
McCabe added: "How many more players will have their careers, and, more importantly, their lives and long-term health put at risk by the sport's inability to follow its own protocols?
"Put simply, the decision to allow Fabian Schar to return to the field of play after suffering a clear concussion was not only incredibly dangerous, but also a clear dereliction of duty.
"The player's comments after the match are also deeply disturbing, and again show the lack of awareness and understanding among players.
"UEFA must immediately launch an investigation into the incident and explain why their protocols were not followed."
Newcastle's medical team are in contact with Switzerland ahead of tomorrow night's Euro 2020 qualifier against Denmark.
UEFA are yet to comment on the incident.