Beijing - Usain Bolt beat his controversial rival Justin Gatlin by just one-hundredth of a second on Sunday as he retained his world 100m title in a race billed as a battle between clean sports and doping.
Bolt, also the double Olympic gold medallist and world record holder, ran his season's best of 9.79 seconds in a thrilling race against Gatlin, who has served two doping bans.
Gatlin overstretched and faltered through the closing stages, taking silver with 9.80 - slower than his semi-final time of 9.77 set earlier at the Bird's Nest stadium.
Gatlin's fellow American Trayvon Bromell and Canadian Andre de Grasse shared the bronze medal position after both timing 9.92.
"That still was not the best. I still stumbled," Jamaica's Bolt said in reference to clumsy footwork close to the blocks, after a similar error nearly derailed him in the semi-final.
"I came out here relaxed, no stress and brought it home.
"My aim is to be the number one until I retire and therefore I am pushing myself and pushing myself.
"It's all about running the race and getting it done. You can call that race rusty, I could have run faster."
Tempered applause rang hollow round a packed Bird's Nest stadium when Gatlin, in a red one-piece suit, was introduced to the crowd.
Bolt, wearing lycra shorts and singlet in the green, gold and black colours of Jamaica, was placed in lane five, Gatlin in lane seven of the nine-lane track.
The towering Jamaican, who celebrated his 29th birthday on Friday, was greeted with massive cheers at the stadium in which he took the world by storm at the 2008 Olympics with treble sprint gold, before repeating the feat in London in 2012.
Chants of "Usain Bolt" rang around along with acclaim for China's Su Bingtian, Bolt raising his eyebrows at a classical piano rendition from a Chinese musician and checking out his beard as his face featured on the big screen.
In their first meeting over 100m since the last final in the Moscow worlds in 2013, when Gatlin also came second to Bolt, the American suffered from a slower start than the Jamaican.
Gatlin, a renowned fast starter who hasn't lost over 100m or 200m since 2013 and has set personal bests for both distances - 9.74 and 19.57 - this season, pegged equal with Bolt out of the blocks.
Sandwiched between Mike Rodgers in four and Tyson Gay in six, Bolt, head down for the first 40 metres, moved into his "drive phase", unbuckling his long, powerful legs, but didn't dare look across the field until a savage dip at the line saw him win a memorable race.
With allegations of widespread doping dominating the build-up to the worlds, the Jamaican's showdown with the sport's pantomime villain Gatlin was portrayed by some as a symbolic struggle of light versus dark.
Gatlin has served two doping bans and since his return to action in 2010 has won 2012 world 60m indoor gold, London Olympic 100m bronze and Moscow world silver, and is currently in the peak of his form at the age of 33, with an unbeaten streak of 28 races dating back to August 2013.
Although Bolt is the first to decry the idea that he is the "saviour" of track and field, global athletics chiefs will no doubt, at least in private, heave a huge sigh of relief at his win.