In addition to the World Cup's first affirmative use of goal-line technology that saw one of the three goals France scored against Honduras confirmed by camera, a far simpler innovation is making its presence felt.

A simple can of "vanishing spray" is being employed by referees to prevent the age-old tactic of defensive walls edging forward at free kicks.

Now, when a free kick is awarded near the penalty area the referee sprays a circle around the ball and paces out 10 yards from the site of the infringement.

A line is then sprayed on the pitch marking the position where the defensive wall must stand.

The marks disappear within a minute and so far the system has stopped the incessant shuffling forward of defenders and at the same time prevented players earning yellow cards.

Employed previously in Brazil and Argentina in domestic football, the vanishing spray was trialled at international level during last summer's Under-20 World Cup and also featured at the Club World Cup in December before getting the green light for the showpiece tournament in Brazil.