World players' union FIFPro has called for an investigation into FIFA's concussion protocol after Uruguay's Alvaro Pereira was allowed to play on despite taking a blow to the head against England at the World Cup on Thursday.
Pereira was struck on the head by the knee of Raheem Sterling in the second half of Uruguay's 2-1 win and received treatment on the pitch before returning to the action.
According to FIFPro, the player himself demanded to play on despite the advice of the national team doctor, but the union wants a change to protocol to better protect players.
"FIFPro is calling on FIFA to conduct a thorough investigation into its own competition concussion protocol which failed to protect Uruguayan footballer Alvaro Pereira during the World Cup match against England on Thursday, June 19," read a statement.
"The World Footballers' Association is seeking urgent talks and immediate assurances that FIFA can guarantee the safety of the players, which must be priority number one, for the remainder of this tournament and beyond."
The union suggested a number of solutions, including the use of independent doctors not affiliated to teams, as well as the possibility of temporary substitutions while players are properly assessed.
The statement added: "Football is awash with incidents in which players suffer potentially concussive blows to the head and stay on the pitch. In Pereira's case, he demanded to play on, overruling advice from Uruguay's team physician for him to be immediately substituted.
"FIFPro understands that in certain moments, faced by the pressures of such an important international stage, many players would react in this way. There are times, however, when the players also require greater protection against the prospect of making any rash decisions.
"Furthermore, FIFPro states any sideline concussion assessment must not be conducted solely by a national team physician. In order to ensure real independence, FIFPro's involvement, as the international authority representing the interests of the players, would ensure they are insulated at all times."