Video refereeing: Watch this penalty decision and vote on whether the system works
The Under-20 World Cup in South Korea is the latest tournament to trial video assistant referees (Var) - and it has seen a number of controversial decisions.
Football's rule-makers want video referees in place as soon as possible and Fifa president Gianni Infantino wants the system ready for the 2018 World Cup.
But is it conclusive? Does it actually work?
Take a look at this decision in the Uruguay v Venezuela semi-final on Wednesday and let us know what you think.
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What else has happened?
Tottenham winger Josh Onomah was given an odd red card in England's quarter-final victory over Mexico when attempting to dribble past an opponent, for which the video referee was not used.
Earlier in the tournament, an Italian player was dismissed after the video assistant referee intervened, while in the opening game, Argentina forward Lautaro Martinez was sent off for elbowing an England player, which the referee initially missed.
Where else has it been used?
- First used in an international friendly between Italy and France in September 2016
- Then used to correct two decisions in another friendly between Spain and France, May 2017
- Used in the Australian top-flight A-League - the first domestic competition to trial it - in April 2017
- The English FA want to trial it in domestic cup competitions from August, possibly in the EFL Cup