Jamaican sprinter Usain Bolt has been sensationally disqualified for a false start at the men's 100-metres final at the World Athletics championships in South Korea.
Bolt, the world-record holder, had been the strong favourite to win.
The defending champion and Olympic gold medallist knew immediately he had made the error.
The 24-year-old ripped off his singlet in disgust and slowly retreated to the starting line, head in hands, to be steered off the track.
Under new rules sprinters do not get a second chance and are instantly disqualified for breaking before the gun.
The race was won by fellow Jamaican Yohan Blake.
American Walter Dix, who won the silver medal, says the rule introduced last year is killing the event and he hopes the International Association of Athletics Federations (IAAF) will change it for next year's London Olympics.
In a statement, IAAF said it was important to remember that a sport's credibility depends on its rules, which must be applied consistently and fairly for all athletes.
Prior to the rule change, athletes had the right to make one false start and were disqualified for a second.
