VAR allows referees to take a look at key moments in order to review their decisions. It debuted at the World Cup this year after almost a decade of consideration. While American football has been using the technology for years, it's taken much longer to for video assistant referees to make its way to soccer (or football, as it is known everywhere except the US).

"We are confident that introducing Video Assistant Referees in August 2019 will give us enough time to put in place a robust system and to train match officials to ensure an efficient and successful implementation of VAR in the UEFA Champions League, the world's flagship club competition," UEFA President Aleksander Čeferin said in a statement.