The light-heavyweight is a substitute teacher by day but on Saturday delivered a blistering lesson to Cuba’s David Morrell The light-heavyweight is a substitute teacher by day but on Saturday delivered a blistering lesson to Cuba’s David Morrell L ast Saturday night in Manchester, Zak Chelli, a 28-year-old supply teacher from Fulham, produced one of the sporting upsets of the year when he knocked out Cuba’s esteemed David Morrell in a stoppage as shocking as it was compelling. Chelli had been