Usain Bolt won a third successive Olympic 200m gold on Thursday to keep his hopes of an unprecedented ‘triple triple’ alive and deliver a perfect tonic to the doping-tainted world of track and field.The victory in his favoured event was Bolt’s 13th individual world or Olympic sprint title from a possible 14 since he took athletics by storm at the 2008 Beijing Olympics.The 29-year Jamaican timed 19.78 seconds for gold, Canadian Andre de Grasse taking silver with 20.02sec and France’s Christophe Lemaitre winning bronze (20.12).As Guns N’Roses’ ‘Welcome to the Jungle’ blasted out, huge cheers greeted Bolt, wearing black lycra shorts and a singlet in the green, gold and black colours of Jamaica.The sell-out Olympic Stadium crowd, which has been criticised for its jeering of some athletes, were raucous in their welcome of the Jamaican star.Bolt, in his favoured lane six, had Lashawn Merritt, the American 400m specialist and sole US hope of a medal after Justin Gatlin failed to make the eight-man final, just inside him.Immediately out of the blocks, the Jamaican was quickly up on Lemaitre, racing in seven.With temperature around 27 degrees Celsius (84F) and the track shining after a light shower of rain, Bolt delivered electrifying control around the bend, hitting the back stretch in full tilt.As the crowd roared, Bolt responded by moving into his famed ‘drive phase’, head coming slowly up as part of the process that unleashes the full power from his long legs.Eyes glued on the stadium’s big screen at the end of the 100m track, Bolt blasted through the line with a glance leftwards at the giant stopwatch.There had been no easing up, but Bolt looked to be left disappointed with his time, ripping the numbers off his shorts and throwing them to the floor.That was quickly forgotten as Guns N’Roses was switched for Bob Marley’s ‘One Love’, and Bolt, draped in Brazilian and Jamaican flags, did a lap of honour to chants of ‘Usain Bolt, Usain Bolt!’ after another amazing victory and eighth Olympic gold.