final, breaking the Olympic record by 0.2 seconds and matching the world record. His official time of 9.9 seconds in the semifinals did not count for records purposes because of wind assistance. Results First round The top three runners in each of the 10 heats advanced. The Official Report describes the weather for these heats as 'rainy'. The wind varied widely, between a 2.85 m/s headwind (in heat 3) and a 1.60 m/s tailwind (in heat 6). Heat 1 Heat 2 Wind, -2.51 m/s Heat 3 Heat 4 Heat 5 Heat 6 Heat 7 Heat 8 Heat 9 Heat 10 Quarterfinals The top four runners in each of the four second round heats advanced to the semifinals. The weather was cloudy and winds were tailwinds throughout. Quarterfinal 1 Wind, +1.90 m/s Quarterfinal 2 Quarterfinal 3 Quarterfinal 4 Semifinals The top four runners in each of the two semifinals advanced to the final. The weather was described as "fine," with lower humidity than the first two rounds and a temperature of 23.8 degrees Celsius. There was a strong tailwind for the first semifinal and a moderate headwind for the second. Semifinal 1 The tailwind speed of 5.28 m/s meant this semifinal was ineligible for record purposes. Semifinal 2 Final Until the Tokyo Olympics world records were measured by officials with stopwatches, measured to the nearest tenth of a second. Although fully automatic timing was used in Tokyo, the times were given the appearance of manual timing. This was done by subtracting 0.05 seconds from the automatic time and rounding to the nearest tenth of a second, making Hayes' time of 10.06 seconds convert to 10.0 seconds (a new Olympic record and matching the existing world record), despite the fact that the officials with stopwatches had measured Hayes' time to be 9.9 seconds, and the average difference between manual and automatic times was typically 0.15 to 0.20 seconds. This unique method of determining the official time therefore denied Hayes the record of being the first to officially record 9.9 seconds for the 100 meters. The first official times of 9.9 seconds were recorded at the "Night of Speed" in 1968. The final was run in "fine" weather, with a tailwind of just over a metre per second. Hayes ran on lane one, which had been damaged by competitors in the men's 10,000 metres and the men's 20 km walk. Nevertheless, his "margin