VAR
The Video Assistant Referee (VAR) made its debut in English football during a January FA Cup tie between Brighton & Hove Albion and Crystal Palace as the game's governing body trials the new technology before introducing it into the sport en masse.
The system, which will allow a fifth match official to watch events on camera and alert the referee if he has made a "clear and obvious error" in a potentially game-changing situation, has garnered mixed reaction from fans, managers and pundits alike.
VAR can only be used for goals, red cards, penalties and mistaken identity, with the video assistant having until the game next restarts to intervene.
The technology also took place in the EFL Cup semi-final between Chelsea and Arsenal and will be available for the final of that competition too.