Usain Bolt, the world's fastest man, could possibly run 9.4 seconds over 100 metres at this year's London Olympics, Games organising committee chairman Sebastian Coe said.
Asked about media reports that Bolt was planning an assault on his world record of 9.58 in London, Coe said that Bolt had the ability to tear up the laws of physics.
"I do seem to remember scientists telling people if they tried to break the four-minute mile, they would probably die in the process," the twice Olympic 1,500 metres gold medallist said in an interview.
"I remember scientists telling me it was probably unlikely that anybody would run significantly under 1:43 for 800 metres," added Coe, whose world record of 1:41.73 stood for 16 years.
"David Rudisha (the Kenyan 800 metres world record holder) is quite capable of running a chunk under 1:41.
"I do think it's possible (for Bolt to run 9.4) but also having watched the extraordinary performances of Yohan Blake, his countryman...
"And Tyson Gay in the States is not going to be a pushover either. I'm absolutely convinced that Usain can run faster, but this will be a Games that's very competitive at 100 and 200."
Despite his zero-tolerance stance towards doping, Coe said it was dangerous to treat every superhuman performance as suspicious because of a disgraced minority of cheats.
"Nobody comes from nowhere," he said. "Usain Bolt has been around a long time working very hard.
"It's far too easy to simply say 'they've made rapid and dramatic progress and therefore they're on some kind of illegal supplement'. That's rarely the case.
"I broke 12 world records and won two Olympic titles and would no more have jumped off Beachy Head than taken any supplement."