Uruguay defender Alvaro Pereira has apologised for the "moment of madness" which saw him ignore the team doctor after suffering concussion in the 2-1 World Cup win over England.

A coming together with Raheem Sterling left Pereira briefly unconscious during the clash in Sao Paulo yesterday, but the left-back shunned doctor's orders to leave the field of play.

The incident has since prompted serious questions to be asked about FIFA's concussion policy, and the player himself admits that he was not in the right frame of mind to make such a decision.

"It was a moment of madness... I've apologized to the doctor because I know it's his job to look after the players," he told reporters.

"I went back on dizzy but, in the heat of the moment, with a hot head, you don't think properly. Still, it was a time to help the team and to get a result. And the most important thing is that we got the result."

Luis Suarez netted an 85th-minute winner to earn Uruguay's first victory of the World Cup thus far.