Usain Bolt always thought he could run a fast 100m. The tough part was convincing his coach, Glen Mills.

Mills had thought of the lanky Bolt as the next great 400m, but the 21-year-old had different dreams.

Bolt often wondered: Could the speed that made him the world 200m silver medalist and world junior record holder also make him a contender in the more glamorous 100m?

Jamaica's Usain Bolt leads Rodney Martin (R) of the US and Wallace Spearmon of the US as he heads to victory in the men's 200 metres at the London Grand Prix at Crystal Palace in London July 26, 2008. [Agencies]

After much discussion, he and Mills reached a compromise last year - if Bolt broke Donald Quarrie's Jamaican 200m, he could run one 100m race.

Down went the record, Bolt running 19.75sec at the Jamaican championships, and his fairytale run to the 100m world record was ignited. In his first 100m race last year, he clocked 10.03, third-fastest by a Jamaican.

"After that there was no stopping him," Mills said.

Both him and Bolt agreed that the 100m would only be his opening act, with the focus still remaining on winning 200m gold at Beijing.

Until, out of the dark of a Kingston night in May, he became a very serious player at 100m.

The 21-year-old ran 9.76, the second-fastest 100m of all-time, in only his third century sprint.

Mills thought that Bolt probably could have broken countryman Asafa Powell's then-world record of 9.74, had he not looked around and slowed 80m into the race.

On the last day of May in a New York meeting with world champion Tyson Gay, he became the world record holder.

Running a near-perfect race, he eased his lengthy frame out of the starting blocks and roared to a time of 9.72, two hundredths of a second faster than Powell's world record.

"In terms of ability, Usain has the most of any athlete I have ever coached and probably have ever seen," said Mills.

Now, Bolt has finally decided to take part in both the 100m and 200m in Beijing.

His astounding progress has already ensured that the blue-riband event will be among the most competitive race ever in Games history.