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."