Bolt clocked a world-leading 19.55 seconds to extend his domination of sprinting since taking the world by storm at the 2008 Beijing Olympics at the same Bird's Nest stadium.

Gatlin, who has served two doping bans, clocked 19.74sec, with South African Anaso Jobodwana taking bronze with a national record of 19.87sec.

The victory meant Bolt has now remarkably won 11 of the last 12 individual Olympic and world sprint titles since shooting to fame at the Beijing Games, his only blip coming after a false start in the 100m at the 2011 worlds in Daegu.

Huge cheers greeted Bolt, wearing lycra shorts and singlet in the green, gold and black colours of Jamaica, placed in lane six, with Gatlin on his inside in lane four of the nine-lane track.

Applause also rang out for Gatlin, in a red one-piece suit, the tannoy presenters building up the atmosphere to mirror a boxing match at a packed Bird's Nest.

The American, as in the 100m, suffered from a slower start than Bolt, who shot out of his blocks. Gatlin, a renowned fast starter who hasn't lost over 200m since 2013 and has set personal best of 19.57sec this season, looked threatening coming off the bend.

But sandwiched between Britain's Zharnel Hughes and Jobodwana, Bolt, in fult tilt after an electrifying bend, responded by moving into his famed "drive phase", unleashing the full power from his long legs.

Unlike the 100m, when it came down to one-hundredth of a second to separate Bolt from Gatlin, there were no such doubts this time.

And Bolt, also reigning double Olympic champion and world record holder over 200m, knew it, thumbing himself in the chest as he crossed the line in a message to the many doubters he has had this season after pelvic joint pain kept him out of competitive action for six weeks.

Gatlin, in the form of his life at the age of 33, previously won world 200m gold in Helsinki before testing positive for testosterone and serving a doping ban between 2006-2010, something he credits with having extended his longevity having sat out four years of hard, competitive racing.

And for a sport mired in doping allegations in the build-up to the worlds, Bolt, one of athletics' most tested stars, again stepped up to the mark not only to help boost the integrity and credibility of track and field but also cement his legendary status.