LONDON - For the first time since automatic electronic timing began, the Olympic 100m field includes all four of the fastest men on earthThey say that the average adult reads at a speed of 300 words per minute when they are paying attention and around double that if they’re not. Which means, assuming that you are being conscientious, that Usain Bolt can run the 100m in less time than it has taken you to get to this full stop.Even compared to the 1988 final, which included three world record holders in Carl Lewis, Ben Johnson, and Calvin Smith, this summer’s 100m is going to be the most competitive race in the modern era of the Olympics. For the first time since automatic electronic timing was introduced, the field will include all four of the fastest men on earth: Bolt, Tyson Gay, Asafa Powell and Yohan Blake. Justin Gatlin has also qualified. The world record of 9.77sec he set in 2006 would rank him fifth-fastest behind those four, but it was struck off when he was banned for testosterone use. As it is, his current personal best of 9.80sec, set at the US trials on 24 June, ranks him joint-seventh on the all-time list.At every other Games between 1968 and 2008, at least one of the four fastest men on the planet at the time has been missing, whether it was Jim Hines, Lewis, Leroy Burrell or Tim Montgomery. It is surprising how many Games have taken place without the current world record holder being in the field, let alone all of the top four men in the all-time rankings. The 2012 final may not be the fastest race in history – the weather alone could see to that – but it is bound to be the most fiercely contested.That brings its own pressures. Ten seconds is so little time, but in an event where the margins are measured in hundredths of seconds it is still more than enough for all manner of thoughts to run through the mind. Even for the fastest men on earth, speed of thought outstrips fleetness of foot. And the one depends on the other. At the 1972 Olympics the Ukrainian Valeriy Borzov, like Bolt in 2008, won the 100m and 200m double. In an interview recorded after his victories, Borzov revealed the favourite training exercise of his first coach, Boris Voitas."We made paper tubes and Voitas would order us to run 100m holding them in our teeth. The one who did not bite or squeeze the tube was considered a sprinter. The rest were considered to be simply runners. This helped me develop the main quality of a sprinter – the ability to relax.”Tension inhibits speed. The moment a sprinter starts to worry about what the man next to him is doing, his muscles tighten and he starts to slow down. Lewis was guided by the principle, taught to him by his coach Tom Tellez, that "human beings can run full speed for 10 metres”, which made it pointless to try and run flat out for the full 100. His rivals, he felt, were so obsessed with getting ahead of him at the start that they began to decelerate by the time they reached 90m, and would tighten up more as they felt Lewis come up on them."Don’t worry about anybody else in the race,” Tellez taught Lewis. "Just worry about what you’re doing. If they are ahead of you, don’t worry, just keep accelerating through 60m to 70m in the race, they will come back to you at the end.” Bolt has a similar approach. "Last 10 metres, you’re not going to catch me,” he says. "No matter who you are, no matter what you’re doing, no matter how focused you are, no matter how ready you think you are, you’re not going to catch me.”"In the 100m,” says Lewis, "a single mistake can cost you victory.” He was not talking about technique – Bolt’s, for instance, is infamously poor, with too much lateral movement, which pushes him sideways off the blocks rather than propelling him down the track – but the negative thoughts that slip into a sprinter’s head during a race. Bolt has never seemed to worry about anything much, least of all what anyone else is doing. Plenty has been said about the advantage his height gives him – his legs are so long that at full speed he covers 10 metres in three and a half strides. But it is Bolt’s temperament that really sets him apart. Pressure runs off him like water off wax. His shenanigans on the start line at the Beijing Olympics, when he struck poses and played up to the crowd and camera, showed a man at ease with himself and the situation he was in. His finish, when he was beating his chest as he crossed the finish line, was so insouciant that some athletes actually found it offensive.And then at the 1985 Zurich Weltklasse, Lewis lost to Ben Johnson for the first time. Lewis was never as dominant again, losing to Johnson at the 1986 Goodwill Games, the 1987 world championships, and the 1988 Olympic final. Until, of course, Johnson was banned and the results were overturned.BOLT VS BLAKE It is unlikely that Bolt’s defeats to Blake in the 100m and 200m at the Jamaican trials will cause a similarly dramatic tilt in the balance of power, because Blake’s time of 9.75sec is still so far behind what Bolt is capable of. But those losses, coupled with the doubts surrounding his fitness, his false start at the 2011 world championships, and his patchy form this year, will surely have put a hefty dent in Bolt’s confidence. At the trials there was an obvious difference in his demeanour. He did not play around on the start line, but stood stock-still, staring down the track. The happy-go-lucky attitude was gone. He looked worried.Bolt has lost before, to Gay for instance, but he always won when it mattered most. Now, for the first time in a long time, Bolt is lining up against a man who he knows has had the beating of him in practice and competition. It is telling that Glen Mills, the coach at the Racers Track Club, in Kingston, Jamaica, has kept the two men apart in training. Blake says he made a point of trying to beat Bolt in practice, because it gave him an edge when the two men met in competitive meets. What kind of toll has that taken on Bolt? How will he react if, like Lewis, he finds himself racing a competitor who he knows is quicker out of the blocks and who won’t just "come back to him” in the last phase of the race?Time and again in the last 12 months Bolt has said that he wants to become a "legend” at these Olympics, though most people would say he already is one. His only opponent, it seemed, was going to be the clock. He spoke about wanting to run under 9.50. Instead he will be judged by another measure – how he handles the pressure of the competition. It could spur him on, or it could hold him back. In 16 days we will know.Bolt must feel he has the measure of Powell. Gay, still the only other man to have run the 100m in under 9.70 without wind assistance, once seemed like the man who would challenge Bolt. But after extensive hip surgery, his body may now be too damaged for him to touch those kinds of times again. Gatlin, however, is a real contender, despite the long odds the bookmakers have put on him.