Collina said: "After 48 matches, the average (number of yellow and red cards given) is 3.4. It's absolutely the level of the major club competitions in the world... The number of red cards is definitely lower than the average in those competitions, and I am happy to say that the three red cards given so far are... related to play, one straight red card... and two red cards for second yellow cards...

"(This is) something that proves... the respect of the players for their opponents so far has been very good. In terms of yellow cards, we told our referees to be very accurate in protecting the image of the game and the safety of the players, the number is absolutely on the repeating line with figures from major competitions."

He added that 24 penalty kicks have been given at this year's tournament, including seven of them taken with the support of the video assistant referee (VAR) system. This is considerably more than at the previous World Cups, with 10 penalty kicks given both in 2010 and 2014.

VAR allows match officials to review video replays of game episodes in order to avoid possible mistakes. The tournament in Russia is the first World Cup where VAR is being used.

The 2018 FIFA World Cup kicked off on June 14 and will continue until July 15, with the matches being played in 11 cities across Russia.