South Africa’s Wayde van Niekerk ran the fastest single lap in history to win the Olympic 400 metres gold medal in 43.03 seconds and break Michael Johnson’s 17-year-old world record on Sunday.

Running an extraordinary race in lane eight, the 24-year-old world champion got off to a flier and was streaking clear on the back straight before upping his pace even further to better American Johnson’s 1999 mark of 43.18 seconds.

“I believed I could get the world record,” Van Niekerk told reporters. “I’ve dreamed of this medal since forever. I am blessed.”

The South African flew across the line a good five metres ahead of 2012 champion Kirani James and held his hands to his head in disbelief before being embraced by the Grenadian, who took silver in 43.76.

“I’m happy to be part of a race that made history,” James said. “We have put this sport on a pedestal.”

LaShawn Merritt of the United States, the 2008 Olympic champion, claimed bronze in 43.85, the first time the top three had run under 44 seconds in the one-lap Olympic final.

“It was a crazy race, a great moment in history,” said Merritt, who was unable to defend his title in London after suffering a hamstring injury in the heats.

“The world record was broken, the best man won.”

American Johnson, who won back-to-back Olympic titles in the event in 1996 and 2000 and is considered one of the greatest sprinters of all time, was dumbfounded by the quality of Van Niekerk’s finish.

“Oh my God! From lane eight, a world record,” Johnson said on the BBC. “He took it out so quick. I have never seen anything from 200 to 400 like that.”

Van Niekerk marked himself as the leading contender for Rio when he led home Merritt and James with an exceptional run to win gold at last year’s world championships in Beijing, where the podium again all ran under 44 seconds.

This year, he became the first sprinter to run the 100 below 10 seconds, 200 under 20 seconds and 400 in less than 44 seconds before deciding to concentrate on the longest distance in Brazil.