English referee Howard Webb tries the vanishing spray to mark out the distance for a defensive wall from a free-kick during a seminar for 2014 FIFA World Cup referees on March 27, 2014 at the home of FIFA in Zurich. The seminar included fitness test for 2014 FIFA World Cup, exercises with football players, physical exercises and theoretical sessions. AFP PHOTO / FABRICE COFFRINI        (Photo credit should read FABRICE COFFRINI/AFP/Getty Images)