Moscow - Despite lingering doubts about the use of video assistant referee (VAR) in Russia, FIFA's refereeing bosses insisted on Tuesday that it will help - not hinder - officiating at the World Cup.
The VAR system has been the source of confusing decisions and long delays while situations are checked during testing in both the German Bundesliga and Serie A.
FIFA director of referees Massimo Busacca admits the system has been rushed in for the World Cup, but insists officials are ready and VAR will help referees make better decisions in Russia.
"We ran very fast getting it ready, but we are convinced of it," said Busacca at a press conference in Moscow.
"We are ready, we know we must be ready as there can be no experiments here."
Busacca compared the VAR to the teams vying for the trophy in Russia.
"It's like a team who didn't play well before a World Cup, made mistakes but now plays much better," said the Swiss ex-ref.
"No national team arrives at the World Cup perfect - it's the same for us. We know that we have to improve."
Busacca believes delays while situations are checked are worth the sacrifice for lowering the risk of wrongly-awarded goals.
He also said controversial scenes will be replayed on screens at the World Cup stadiums so fans can see why decisions were reached.
He revealed that VAR officials will wear full refereeing kit while sat in the viewing studio in Moscow, so they feel part of the action.
"VAR officials sweat with the stress -- believe me," added Pierluigi Collina, chairman of the referees committee at FIFA.
"They couldn't go into the box wearing a shirt, suit and tie - that is why they will be wearing the kit," explained the former top Italian ref.
Collina said it is time for the VAR to prove it's worth in the modern game, "the time of action has come", but he rejected the notion that it removes some spontaneity.
The presence of the VAR often leaves players unsure whether to celebrate, or wait until the goal is given, after hitting the back of the net.
"Would you rather a wrong goal be celebrated or would you want to cut the celebration?" Collina asked reporters.
"I think the outcome is what counts."
However, the Italian side-stepped the question whether referees had been specifically briefed to halt games - or even order the teams off - if, as feared, there are racist incidents in Russia.
"There is a three-step procedure and they are ready to go through with it if need be," said Collina.
The 'Three-step procedure' means if there is a racist or discriminatory chanting, the referee can pause the match to request an announcement asking for the chanting to stop.
If it persists, the ref can suspend the match and request another announcement, then wait until the chanting stops, but if it still does not cease, he can abandon the game.