Paraguay's Almiron becomes first player to be sent off for covering mouth

The incident occurred towards the end of the first half after Almiron's teammate, Isidro Pitta was fouled, leading to a scuffle between the players in what was a feisty affair.

The referee didn't originally spot the incident, but was alerted to it by VAR, leading to the dismissal of the Atlanta United player by El Salvador referee Ivan Barton.

The rule was brought it before the World Cup by FIFA after Gianluca Prestianni of Benfica covered his mouth to allegedly racially abuse Real Madrid's Vinicius Junior in a Champions League knockout game earlier this year.

In a statement from April, when the new rule was announced, IFAB said: "At the discretion of the competition organiser, any player covering their mouth in a confrontational situation with an opponent may be sanctioned with a red card."

Before that point, both players and managers would cover their mouths to not give away any tactical insight, or, more nefariously, say things that could not be picked up by the TV cameras.