At World Track and Field Championships, look out for a new rising star from South Africa ... and nine other compelling stories

Usain Bolt's farewell to big-time track at the World Track and Field Championships this month in London won't be the only compelling story at the event. A look at 10 personalities to watch in London. My story for ESPN.com: http://www.espn.co.uk/athletics/story/_/id/20230415/iaaf-world-athletics-championships-2017-athletes-our-radar-london