FIFA's referees chief has said he wants shorter delays and less disruption from the use of the video assistant referee (VAR), which is currently being tested ahead of next year's World Cup.
World football's governing body is using the Confederations Cup in Russia to try out the VAR system for the first time at a major senior international tournament.
Qualified referees review game-changing incidents - goals, penalty decisions, red card decisions and cases of mistaken identity - during matches, which gives the referee on the pitch the chance to correct decisions.
FIFA has yet to decide whether the VAR system will be used at next year's finals in Russia, with the system proving controversial at the Confederations Cup for breaking up play.
A VAR review meant there was a confusing four-minute break in Germany's 3-1 win over Cameroon on Sunday in Sochi.
Colombian referee Wilmar Roldan initially booked Sebastien Siani for a high challenge on Germany's Liverpool midfielder Emre Can, even though it was Ernest Mabouka who had committed the foul.
Following a review by the VAR, Siani was instead shown a straight red, but eventually a further review led to the Cameroon player's dismissal being rescinded and a red card shown to Mabouka.
Busacca: "At the moment not everything is working"
Massimo Busacca, FIFA's Head of Refereeing, admitted the confusing delay was too long, but he was ultimately pleased that the correct decision was made.
"I have to agree, it was too long, but the correct decision was made. The right player was sent off," said Busacca on Monday.
"Delays of one, two or three minutes are not acceptable, we have to improve that.
"It's clear, at the moment not everything is working, but in the 12 games there has not been a mistake missed and that is the most important message."
"There are many aspects that should be improved"
The former top Swiss referee said the VAR system is a work in progress, but insisted it has been a success so far.
"Of course, we admit there are many aspects that should be improved. We need to keep the waiting time as short as possible.
"However, choosing the right camera angle as quickly as possible, under pressure, is something that is still not second nature.
"After the conclusion of the tournament, we will work for the future. We have to. We will not be perfect, but we will reduce mistakes and players will know that they are under scrutiny."
Busacca also said that in the future, fans could be able to hear conversations between the referee and the VAR, as happens in other sports, to explain why decisions are made.