The team doctor who watched over France's 1998 World Cup and Euro 2000-winning team claims Tottenham Hotspur "played double or quits" with Hugo Lloris' health at the weekend.
Lloris, 26, lost consciousness after the left knee of Everton striker Romelu Lukaku crashed into the side of his head during Sunday's goalless draw at Goodison Park.
The France international was unaware of the scoreline and had no memory of the incident itself afterwards, but he insisted he would finish the game.
Though a scan carried out in Liverpool after the game showed Lloris had not suffered concussion, the decision to allow him to play on has been criticised by Jean-Marcel Ferret, Les Bleus' team doctor between 1993 and 2004.
"I was with some neurologists, and we all thought that the risk of a neurological traumatism at that moment was very high. It was a blow to the parietal bone, which can be very serious," Ferret told Le Parisien.
"Clearly, if I had been on the pitch at Everton, I would have asked for a substitution. And even if the player had wanted to continue, I would have gone to the coach to ask to take him off. The rule should be simple: a loss of consciousness means you being taken off the pitch.
"In that case, not only should Lloris have gone off the pitch, but he should have been hospitalised immediately to assess his neurological state. In this case, the story ended well, but they played double or quits with Lloris' health."
Ferret's opinion was seconded by one of his successors, Alain Simon, who -- having worked for many years in boxing -- is fully aware of the dangers of blows to the head, as he told L'Equipe.
"There is the risk of a cerebral haematoma," said Simon, who was Paris Saint-Germain team doctor between 1982-92 and 2001-07 as well as the head of the national team's medical staff from 2008 to 2010.
"It's rare, but it happens. Only an MRI scan allows you to rule out the possibility of a micro-haemorrhage in the brain. In the case of Lloris, of course, straight away, he underwent a quick neurological check: the eyes, balance, speech. But as a precaution, if I'd been the team doctor, I would have taken him off."
On Monday, brain injury charity Headway said the North London club showed an "irresponsible and cavalier attitude" to Lloris' health by keeping him on the field.