San Francisco 49ers tight end George Kittle has turned to the World Cup for inspiration, noting that professional soccer matches are held exclusively on natural grass—even in NFL stadiums. Now he’s asking a simple question: if “futbol” can host its biggest stage on grass, why can’t the NFL?

NFL players and fans are ramping up pressure on teams to tear out AstroTurf in favor of real grass. After another star athlete went down on an artificial surface, a telling statistic – a 28 percent higher injury rate – has become a rallying cry.