Football referees will use the recently-developed vanishing spray at the World Cup next year to stop defensive walls creeping forward at free kicks.
Fifa president Sepp Blatter says the spray, developed in Brazil and Argentina, has received a positive reception after being used at the Club World Cup in Morocco.
When a free kick is awarded near the penalty area, the referee paces the regulatory 9.15 metres between the ball and the nearest defender and then sprays a line on the pitch to mark the correct position of the wall. The line then disappears from the pitch within a minute.
It has been used for several years in Argentina and Brazil where it is generally accepted that it has reduced the amount of arguing over where the wall should stand and prevented encroachment.