Mo Farah challenges Usain Bolt to a race over distance chosen by fans

• Farah believes 600m to 800m race would be fairest • Bolt turned down 400m challenge from David Rudisha Not content with outdoing the world's greatest long-distance runners twice in last year's Olympics and carrying the burden of favouritism into this year's world championships, Mo Farah has sought to make his life just a little bit more difficult by challenging the fastest man in history to a race over a mutually-inconvenient distance. Farah and Usain Bolt share an agent and a friendship, ...