Video assistant referees will be used at the World Cup for the first time in this year's finals in Russia, FIFA president Gianni Infantino says, and teams will be allowed a fourth substitute in matches that go to extra time.
The use of the VAR system was approved this month by the rule-making body IFAB, despite controversy in some of the competitions in which it has been trialled over the time taken to make decisions and lack of information for spectators.
"We are going to have our first World Cup with video assisted refereeing," Infantino told reporters on Friday after a FIFA Council meeting.
"It's an essential decision, very important and historical decision."
The system allows the referee or the video assistant to review decisions where a "clear and obvious" error is spotted.
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It has been trialled in Germany's Bundesliga and Italy's Serie A this season and some English FA and League Cup games, among others.
Infantino said VAR had been shown to reduce the number of refereeing mistakes in matches where it has been used and would help football become "a fairer and more transparent sport".
FIFA Council member Reinhard Grindel tweeted that clear communication would be important to make the system a success.
Referees can call on VAR to review and overturn "clear and obvious errors" plus "serious missed incidents" involving goals, penalty awards, red cards and mistaken identity.
Infantino had repeatedly promised VAR would be used at the June 14-July 15 World Cup and has made it one of his priorities since being elected FIFA chief in 2016.
FIFA also said that, where matches went to extra time, teams would be allowed a fourth substitute, a rule change also approved by IFAB.
Infantino said the hosts for the 2026 World Cup, to be decided at the FIFA Congress in Moscow in June, would be chosen in an open vote by its member national associations and details of how they voted would be published.
He confirmed there were two candidates - Morocco against a joint bid from the United States, Canada and Mexico.
