MOSCOW — The shine from Mexico’s opening-game victory over Germany was dulled Monday when The Associated Press reported FIFA has opened disciplinary proceedings against the team because its fans used an anti-gay slur during the game.

Some Mexican supporters chanted the slur when German goalkeeper Manuel Neuer prepared to take a goal kick in the 24th minute of Sunday’s game at the Luzhniki Stadium. Fans of the Mexican team use the chant to insult opposing goalkeepers as they take a goal kick.

The Mexican soccer federation has been repeatedly fined by FIFA over fans chanting the slur but the sanctions haven’t escalated. The federation and players previously have urged fans to stop the chant through public statements but that has proved unsuccessful.

FIFA did not elaborate on the nature of the disciplinary proceedings and didn’t say when a hearing would take place.

“We cannot comment further at this stage,” FIFA said in a statement.

FIFA, under pressure to stop racist and anti-gay activity in Russia, is using a new anti-discrimination procedure for the World Cup. Under the procedure, referees are instructed to stop the game for an announcement on the public-address system when discriminatory behavior is seen or heard. If it continues, the official can suspend the game, and then abandon it if the behavior persists.

That procedure was not used Sunday.

“A public announcement was prepared, but the chants ceased,” FIFA said.