A showdown between two of the fastest men in the world is on course to go ahead this afternoon as Olympic and world champion Usain Bolt goes head-to-head with America's Justin Gatlin.
Gatlin, who has been suspended twice on doping offences, shrugged off audible boos from the crowds and clocked the highest time in the heats with 9.83 seconds.
World record holder Bolt, whose season has been disrupted by joint problems was satisfied with going under 10 seconds in his heat, ranking fifth overall.
The World Championships semi-finals will take place this afternoon, followed by the hotly anticipated final showdown.
Mo Farah put a summer of speculation behind him to make it half a dozen global titles as he again proved unbeatable over 10,000 metres at the World Championships in Beijing.
Farah was ruthlessly focused amid all the off-track distractions as he burst away from the twin Kenyan challenge of Geoffrey Kipsang Kamworor and Paul Tanui down the home straight.
The 32-year-old has endured a tumultuous year, caught up in the doping allegations surrounding his coach Alberto Salazar, but has not lost his aura of invincibility on it as he came home in 27 minutes 01.13 seconds.
Justin Gatlin responded to boos from the Beijing crowd by storming to 9.83 seconds in the heats of the 100 metres at the World Championships.
The two-time drug cheat, cast as athletics' number one villain, especially in the wake of the doping crisis which has engulfed the sport in recent weeks, looked mightily impressive in qualifying fastest for Sunday's semi-finals at the Bird's Nest stadium.
Gatlin's introduction was greeted with audible jeers, but his time was an emphatic statement of intent, even with a marginally illegal following wind.
It was faster than Usain Bolt has run all year and suggests he is in shape to go faster than his world-leading personal best of 9.74secs come the business end of the competition.
Jessica Ennis-Hill lay in gold medal position after three events of her heptathlon as she made a strong return to the global stage at the World Championships in Beijing.
The Olympic champion, in her first major championship since London 2012 and 13 months after the birth of her son Reggie, was on 2,968 points, 34 clear of Belgium's Nafissatou Thiam.
Team-mate and rival Katarina Johnson-Thompson was also going well, despite dropping down to ninth on 2,854 after the shot put, her weakest event.
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Sebastian Coe has been elected as president of the International Association of Athletics Federations.
Former British Olympic 1500m Champion Lord Coe beat Ukrainian pole vaulting legend Sergey Bubka by 115 votes to 92 in a ballot of IAAF congress members.
The governing body of world athletics has fiercely denied claims made in The Sunday Times that it blocked the publication of research that showed a third of top athletes had admitted cheating.
ITV News's Peter Smith reports:
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World athletics' governing body has dismissed newspaper claims it blocked a 2011 doping study that allegedly revealed a third of top athletes had admitted cheating.
In response to the Sunday Times report, the International Association of Athletics Federations (IAAF) said: "This is not a new story, having first been raised on German TV in 2013, and those concerns were addressed by the IAAF at the time."
The study in question was a social science based survey conducted by WADA and a team of researchers at the Athletes’ village in Daegu. The purpose of the study was to assess the reliability of potential new methods of evaluating the prevalence of doping in sport using more of a social science approach (randomised-response survey). The survey was intended to be extended to multi-sport events and no publication was ever evoked. In fact, the survey was only ever repeated once, with a revised methodology, at the Pan-Arabic Games where mainly athletes were interviewed.
The IAAF was therefore surprised when it was informed in early 2013 that an article had already been submitted by the research team for publication in a scientific journal without the IAAF’s knowledge. The IAAF understands that the article was rejected for publication.
The International Association of Athletics Federations (IAAF) has said it "never vetoed the publication" of an article which claimed that around a third of athletes at the 2011 World Championships admitted using banned performance-enhancing substances, as claimed in a Sunday Times report.
"The IAAF has never vetoed publication of this article," it said in a statement on Sunday.