It was a quarter of a century ago this week that Ben Johnson first dazzled and then rocked the Olympic world. Reuters' Mike Collett recalls the unfolding of a track star's downfall.

Covering sport in 55 countries over the past 40 years I have seen the greats reach the stars and I have seen the stars fall from the heights. But one moment stands out from the rest: watching Ben Johnson run in Seoul on Sept 24, 1988.

The most controlled explosion of disciplined sporting power I have ever witnessed at close quarters lasted all of 9.79 seconds over 100 meters in the men's Olympic final when Johnson destroyed the field - and most emphatically Carl Lewis - to win the Olympic gold medal.