English football is facing questions over its handling of head injuries after the Tottenham goalkeeper was allowed to play on despite being knocked out during Sunday's goalless draw at Everton.
Hugo Lloris was injured in a collision with Romelu Lukaku that left him prone and apparently unconscious.
With his team-mates clearly disturbed, Tottenham’s medical staff rushed to the goalkeeper and decided that he was not fit to continue.
After receiving nine minutes of treatment, however, Lloris defied club doctor Shabaaz Mughal and captain Michael Dawson, both of whom pleaded with him to leave the field, and stayed on.
The French international was praised after the game by manager Andre Villas-Boas for his attitude, but the decision was described as "irresponsible" by brain injury charity Headway.
A spokesman for the charity said: "We are hugely concerned that a professional football club should take such an irresponsible and cavalier attitude to a player's health.
"By continuing to play, the player may have caused greater damage to his brain.
"He should have been removed from the game immediately and taken to hospital for thorough tests and observation."
The treatment of head injuries and concussion has been a major issue for rugby union and American Football, where the long-term effects of repeated blows to the head are of growing concern.
The Rugby Football Union is currently running a concussion-awareness campaign following warnings that it was allowing players with brain damage to continue because of inadequate controls.
In the US, the NFL settled a $750m (£470m) lawsuit with former players amid growing evidence that the game was responsible for causing long-term brain injuries.
Football has faced fewer challenges to its protocols for dealing with head injuries, but the Lloris incident has exposed apparent flaws.
A study by the British Journal of Sports Medicine published last year found that more than half of the 92 English league clubs did not routinely follow the latest guidelines on dealing with concussion.
The study, based on questionnaires sent to all 92 clubs, concluded that: "FA players are not being treated to the guidelines recommended by international sporting organisations."
These guidelines, agreed at a conference in Zurich last year, state that a player diagnosed with concussion "should not be allowed to return to play on the day of injury".
Tottenham issued a statement on Monday in which head of medical services Wayne Diesel said that following a CT scan he was "totally satisfied" that Lloris was fit to continue playing.
The statement also said Lloris was cleared to resume playing "after examination by the club's medical team".
Despite this, both Fifa's medical chief and the international players' union said Lloris should have been substituted pending a full and thorough examination.
FIFPro medical adviser Vincent Gouttebarge said: "FIFPro condemns that the health and safety of players are let to coaches/trainers, or even to players themselves.
"Medical professionals should be aware of any relevant medical guidelines and apply them in order to empower the health and safety on the field.
"The health and safety of the players should be the number one priority and should prevail against any other matters."