BEIJING - Usain Bolt brutally ended two-time doping offender Justin Gatlin's attempt to controversially usurp him as the king of sprinting when he blazed to the 100 metres world title on Sunday. The towering Jamaican roared past Gatlin at the halfway mark to retain his crown in a season's best of 9.79 seconds, with his American rival taking silver just one hundredth behind on a pulsating evening at the world championships in Beijing. Before their blockbuster clash, Olympic champion Jessica Ennis-Hill completed a fairytale comeback by winning her second heptathlon world title, helped in no small part by an astonishing meltdown by fellow Briton Katarina Johnson-Thompson.

But the night belonged to Bolt, who had played a high-stakes game of poker in the heats, running well within himself as Gatlin, dressed in a blood-red lycra suit, posted eye-popping times of 9.83 and 9.77 to seemingly gain the psychological edge. Gatlin, the sport's pantomime villain after twice serving doping bans, looked stunned at the finish as Bolt danced and struck a gunslinger's pose and a Bob Marley tune pumped out around the Bird's Nest stadium, where he shook the world at the 2008 Olympics. "I came out relaxed, no stress, and brought it home," said Bolt, who turned 29 on Friday. "It is all about running the race and getting it done. My aim is to be number one until I retire."

Gatlin, 33, was philosophical after tasting defeat for the first time in 29 races, a streak dating back two years. "I feel good," he shrugged. "It was a great race, I just got nibbed at the line by the great Usain."

Behind Bolt and Gatlin, American Trayvon Bromell and Canada's Andre de Grasse shared bronze after recording a time of 9.92 in a final in which four of the nine men had returned from doping suspension, including Americans Tyson Gay and Mike Rodgers, along with Jamaican Asafa Powell. New world athletics boss Sebastian Coe will privately be breathing a sigh of relief that Olympic champion Bolt repelled Gatlin's challenge after the sport was plunged into crisis by allegations of widespread doping.

Britain's Ennis-Hill, returning to the sport after giving birth last year and a battle with niggling injuries, was all but gift-wrapped the gold medal after Johnson-Thompson failed to post a mark in the long jump. Last world champion in 2009, Ennis-Hill capped a remarkable two days by storming home to win the final 800 metres heat in two minutes, 10.13 seconds to finish as the runaway winner with a total of 6,669 points.

Canada's Commonwealth Games winner Brianne Theisen-Eaton, the gold medal favourite coming into the competition, settled for silver with 6,554 while Latvian Laura Ikauniece-Admidina took bronze with a national record 6,516. A shell-shocked Johnson-Thompson was left languishing a distant 28th on 5,039 points. The 22-year-old came unstuck after deciding to go for broke in the long jump, attacking the board aggressively in a bid to claw back some of Ennis-Hill's overnight advantage.

But her high-risk strategy backfired as she fouled her first two attempts and was red-flagged again despite landing a huge third jump, prompting an official protest from British officials which was quickly withdrawn. Ennis-Hill, who nailed a season's best long jump of 6.43m, gave the young pretender a consoling hug after watching her suddenly crash out of medal contention from second overall.

Among the muscle men, Poland's hulking hammer king Pawel Fajdek retained the title he won in Moscow with a heave of 80.88 metres to make it 16 consecutive victories in all competitions. Tajikstan's Dilshod Nazarov took silver with 78.55, edging Pole Wojciech Nowicki (78.55) into bronze position by dint of having a better second-best throw.

American Joe Kovacs shattered German David Storl's hopes of a hat-trick of world titles to win the men's shot put with a best effort of 21.93 metres. Storl had to settle for silver with a best of 21.74. Spain's Miguel Angel Lopez broke Chinese hearts in the men's 20 kilometres walk early on Sunday, the European champion overpowering Olympic bronze medallist Wang Zhen, who had looked set to win the host country's first gold medal.