Four-times Olympic gold medallist Michael Johnson believes his Grand Slam Track can be the "Formula One of athlete racing," as the novel circuit that puts rivalries at the forefront kicks off in Kingston, Jamaica, from Friday. The four-event start-up comes amid longstanding concern over athletics' popularity outside of the Olympics, as track and field is a regular attraction in Europe but struggles to compete against the "Big Four" of North American professional sport. Johnson, a larger-than-