South Africa's most decorated men's swimmer, Chad le Clos, is up for the fight in his fourth Olympics.

There's a smattering of media and volunteers standing in the mixed zone in the Olympic Park aquatics centre while the evening session is in progress.

We've worked our way through the men's 100m freestyle semifinals, the men's 200m breaststroke semifinals, but now is the big one.

Some crane their necks to get a glimpse of the pool, obstructed by the throng of cameras and TV media, waiting to interview the winner of the men's butterfly gold medal. That would be Michael Phelps, surely? The American is regarded as swimming's GOAT, and perhaps even the greatest-ever Olympian.

He's unbeaten in the event for the past 11 years and he'll take off from lane six, with a 20-year-old South African ball of energy to his left, in lane five.

What happens next is the stuff of sporting legend. With one last lunge to the wall, Chad Le Clos causes one of the greatest upsets in Olympic swimming history.

He wins the gold medal in a time of 1min 52.96sec. It is an African record and still ranks as the fastest Le Clos has...