The Professional Footballers' Association has called for any player who loses consciousness to be automatically removed from the field of play following the controversy surrounding Tottenham goalkeeper Hugo Lloris.
Spurs allowed the Frenchman to stay on the pitch despite being knocked unconscious in a collision with Everton striker Romelu Lukaku during Sunday's Barclays Premier League match at Goodison Park.
The PFA says the rules need changing so that any player who loses consciousness during a match should be automatically taken off - current regulations leave it up to medical staff to make a decision.
Lloris insisted on staying on after Lukaku's knee caught him on the head. He was unable to remember the incident after the match, which is a sign of concussion. He was given a brain scan after the match in Liverpool but was given the all-clear.
PFA deputy chief executive John Bramhall said in a statement: "When treating a player on the pitch, it can be very difficult to determine the severity of a head injury. It is important to take the pressure off the players, club medical staff, and the manager - removing the need for them to make a very difficult decision.
"If anyone suffers a severe trauma to the head and loses consciousness, then they should be required to leave the field of play automatically.
"The PFA will continue to work with the stakeholders within the game, to evaluate what guidelines are currently in place and to see if and how they need to be improved to provide better protection for all those involved in the game."