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 paint a white line 9.15 meters (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 decide if the tests are extended.
Vanishing spray is unlikely to be used at the World Cup in Brazil, though a decision could potentially be taken March 1-2 when FIFA's rules-making panel meets in Zurich.
The spray is popular in South America but is not widely used elsewhere.