Referees at the 2014 FIFA World Cup are using a “vanishing” spray paint to keep players in line at this year’s event in Brazil.

The spray paint, which evaporates or “vanishes” after about a minute, is used by officials to keep players from creeping too close to the ball on free kicks. Referees carry a can of the substance on the field and use it to paint a white line 9.15 meters, or about 10 yards, away the free kick spot; defenders aren’t allowed to cross the line.

The “vanishing spray” made its first World Cup appearance during Thursday’s opening match between Brazil and Croatia, but it will be used throughout the tournament. It’s already a bit hit amongst Twitter users, many of whom have never seen it used during a match.

In May, FIFA President Sepp Blatter explained why the spray paint was approved for use at World Cup matches. "We started using it in all (our) competitions this year and at the World Cup we will definitely keep on the same path,” he said, according to the Associated Press. “For the discipline of the game, it’s good. I was skeptical at first but after talking to referees who used this system, they were all happy with it.”

Over a decade ago, Pablo Silva, an Argentinian journalist and entrepreneur, worked with a group of chemical engineers to invent the spray, Reuters reported. Silva first thought of his invention after a defender in a pick-up game crossed the imaginary 9.15-meter line and blocked his free kick attempt.

''We were losing 1-0 and had a free kick and as I stood over it I knew I could make this left-footed shot and even the game. But when I finally took my shot the ball struck the defender in the stomach as he was just 3 meters away,'' he told the Associated Press. ''I was in a rage and I ran straight to the referee who would eventually show me a red card for protesting. And that's when it came to me.''

The spray was first used during a professional match in 2008, but FIFA only approved its use this year. “We’ve climbed a long, steep curve to get here,” Silva said. “Economically, this will be very important for us but what makes us most proud is that the product will be recognized at an international level. You can’t put a price on that.”