Former Premier League referee Howard Webb believes much work is yet to be done before Video Assistant Referees (VARs) are fully introduced into football.
VARs are currently being tested in several competitions, including the recent Under-20 World Cup and in international friendlies, but Italian referee Davide Massa has been criticised for using the system to send off France defender Raphael Varane in Tuesday's 3-2 win over England.
Massa did not show a card to Varane before consulting the VAR, which goes against the protocol, and Webb says referees still need educating on how the system should work.
"Training is a huge issue," Webb told the Daily Mail. "We have referees who have been refereeing for a long time but we have to change the mindset from what they do on the field to how they can best benefit the game in their role as video assistant refereeing.
"We're investing a lot of time, effort and money to have a positive impact on the game without interference."
Serie A announced at the weekend that it was seeking FIFA approval to introduce VAR from the start of next season.
David Elleray, the ex-referee who wrote the protocol for VAR, is cautious about bringing it in too quickly.
"The biggest problem is the VARs are interfering too much, they are reviewing or checking too many incidents," Elleray said. "They are recommending reviews in too many situations. They are not focusing just on clear errors."