False start Bolt gets thrown out to end his dream; WORLD CHAMPIONSHIPS.
Defending champion Bolt had looked in brilliant form in the heats and semi-final, ironically feeling all the hard work he had done on his start had finally paid off.
But the 25-year-old Jamaican star got it all wrong in spectacular fashion in Daegu, springing from his blocks well before the gun (his reaction time was -0.104 seconds) and pulling his running vest off in despair, instantly realising he would be disqualified.
While a mortified Bolt was still slapping a wall near the start in frustration, a stunned stadium saw 21-year-old compatriot Yohan Blake power to the title in 9.92 seconds, with American Walter Dix taking silver and veteran Kim Collins the bronze.
Bolt was nowhere to be found after the race, while training partner Blake - who did not even compete in the last World Championships in Berlin after testing positive for a stimulant and later receiving a three-month ban - said: "I can't find words to explain it.
"I feel like I want to cry. Trust me, I've been praying for this moment for my whole life.
"I felt sorry for Usain, my training partner. I had to take it out in the race for him. When he did the false start I was so surprised because we had been talking about that in training - he false starts a lot - and now it happens.
"I knew I would challenge Bolt one day, but I did not expect it today. I am traumatised and have mixed feelings, I am very sad for Usain Bolt but at the same time I am enjoying this very much."
Silver medallist Dix - who just overhauled Collins on the line to finish 0.01s ahead of the 35-year-old - said of Bolt's disqualification: "I couldn't believe it, it's kind of surreal.
"I didn't think they were going to kick him out. It's pretty hard to kick Usain out of the race."
Rule 162.7, which was introduced for the 2010 season, states that: "An athlete, after assuming a full and final set position, shall not commence his start until after receiving the report of the gun. If, in the judgement of the starter or recallers, he does so any earlier, it shall be deemed a false start. Except in combined events, any athlete responsible for a false start shall be disqualified."
From 2003, the rules stated that after any false start, all athletes are warned. Any subsequent false start leads to immediate disqualification. Previously, disqualification occurred only after the same athlete false-started twice.
The new rule has not been universally popular, with former world champion Tyson Gay proving eerily accurate when he predicted in June 2010: "If it happened at the Olympics or World Championships next year...without Usain Bolt the race is going to have an asterisk to the side. It just doesn't make sense."
And another former world champion, Trinidad's Ato Boldon, wrote on Twitter: "That sound you hear is the rules committee wondering how they could have ruined a whole meet with a rule no one wanted."
Remarkably, Bolt was the second sprinter to get disqualified in the 100m this evening, with Britain's Dwain Chambers committing a false start in the first semi-final.
"It hasn't really sunk in yet but I've got to keep my thoughts and frustrations to myself at the moment," said Chambers, whose false start was barely noticeable compared to Bolt's. "The gun went and I moved."
What is the false-start rule as it stands? Any athlete who jumps the gun is disqualified. There are no second chances, as Usain Bolt, Dwain Chambers and Christine Ohuruogu found out to their cost.
How does it work? False starts are detected by pressure sensors on the starting block. An athlete does not even have to cross the starting line to be disqualified - as was the case with Chambers - as even a twitch can register on the sensors. Any substantial movement reaction within 0.1 seconds of the gun being fired is considered a false start, as research has shown human beings are incapable of reacting quicker than that. When did the rule come into force? The rule was okayed back in 2009 and officially brought in on January 1, 2010. What happened before then?: Before then, the field was allowed a single false start. A second false start - even from an athlete who did not commit the first offence - led to disqualification. Why was it changed? Officially it was changed to prevent gamesmanship. IAAF president Lamine Diack said at the time: "The current rule gives sprinters the chance to play the system to deliberately false start but not be punished for it." There is a suspicion, though, the decision had as much to do with TV companies - false starts could play havoc with their schedules. What was the reaction at the time? It's fair to say many athletes were unimpressed. Former world champion Tyson Gay said, presciently as it turned out: "I don't like it one bit. If it happened at the Olympics or World Championships next year - without Usain Bolt the race is going to have an asterisk to the side. It just doesn't make sense."
Have any other high-profile athletes been affected? Women's world and Olympic champion Shelly-Ann Fraser who fell foul of the rule at a Diamond League meeting in Rome last June. She said: "It was very devastating and I cried because this was the first time in my career something like this was happening to me. I hate this new false-start rule. I definitely do not like it."
* A dejected Usain Bolt after being disqualified Jamaica''s Usain Bolt, fourth from bottom, false starts from the men''s 100m final at the World Athletics Championships in Daegu