US athlete Justin Gatlin smiles before their heat of the men's 4x100m relay athletics event at the 2017 IAAF World Championships at the London Stadium in London on August 12, 2017. Pic/AFP

A sentimental Justin Gatlin hailed Usain Bolt as an "amazing showman" whose career would certainly not be defined by him pulling up with cramp in the world 4x100m relay, the Jamaican's final competitive race.