Fifa will let referees use a vanishing spray to mark out the distance for a defensive wall from a free-kick during matches at the Club World Cup in Morocco next month.

Referees will paint a white line 10 yards from the ball which defenders must stay behind at a free-kick. The line disappears within one minute.

Fifa's head of refereeing, Massimo Busacca, says feedback from Morocco and trials at Under-20 and Under-17 World Cups this year will help determine whether the tests are extended.

Vanishing spray is unlikely to be used at the World Cup in Brazil, though a decision could potentially be taken in March when Fifa's rules-making panel meets in Zurich. The spray is popular in South America but is not widely used elsewhere.