VAR: Talking point of World Cup 2018

Follow Al Jazeera's coverage of the World Cup 2018 here.

Video Assistant Referee (VAR) is being used at a World Cup for the first time.

Although it has been used in domestic competitions across Europe in the past year, some concerns have been raised about the system. 

Peru coach Ricardo Gareca said human error was one of soccer's charms and that the VAR system was a useful solution but not the perfect one.

"Mistakes will always occur. That's one of football's attractions. It is [my] private perspective," Gareca said on Wednesday, seemingly in defence of referees.

"Football is inextricably linked with mistakes and I don't think this is going to be the perfect solution. It is an add on, it can be helpful."

VAR is only used to decide if a goal has been fairly scored, if a player should be sent off, if a penalty can be awarded or to alert the referee if he mistakenly penalises the wrong player.

And football fans are getting used to the idea that they are not the only ones watching this World Cup on television.

Each game is followed by four officials watching footage from 33 cameras. The on-pitch referee is still expected to make decisions. Only if there is a "clear and obvious error" will VAR intervene.. 

But it’s deciding what a "clear and obvious error" is that leaves room for disagreement.

“Football leaves a lot to interpretation," Pierluigi Collina, FIFA Referees Committee chairman, told Al Jazeera.

"It’s different to to other sports like cricket, basketball volleyball. There will be some inconsistency because what may be clear to one referee is not clear to another."

With additional reporting by Andy Richardson in Moscow.