US superstar Noah Lyles has been crowned the fastest man on earth - by a winning margin so small it could barely be recognised.

Lyles snared the gold medal in one of the Olympic Games’ blue-ribbon events, with the 100-metre final living up to the hype with its closest-ever finish.

Athletes waited for almost a minute post-race as they waited for judges to assess the finishing order, with seven men finishing within 0.09 seconds of one another.

Ultimately, it was Lyles who was crowned champion, edging out Jamaica’s Kishane Thompson by a margin that was deemed as five-thousandths of a second after they finished on the same time of 9.79 sec across the standard two decimal places.

The 27-year-old ripped the name plate off his chest upon being confirmed as the winner, taking off on a victory lap around Stade de France.

“There was a lot of doubt, I’m not gonna lie,” Lyles said after the race, which marked a personal-best time.

“I thought I did not get Kishane there. I thought he outdid me, to be honest.

“When we got off the (finishing) line, I said, ‘I think you got that one’.”

Lyles had been last in the eight-strong field at the 40m mark of the race, but produced a long-striding blistering finish to earn the unforgettable result.

Having claimed bronze in the same event at the Tokyo Olympics three years ago, Lyles said he was thrilled to achieve redemption.

“It’s the one I wanted,” he said.

“It’s the hard battle, it’s the amazing opponents.

“Everybody came prepared for the fight and I wanted to prove that I’m the man among all of them. I’m the wolf among wolves.”

American Fred Kerley secured bronze in a time of 9.81 seconds, edging out South Africa’s Akani Simbine by 0.01 sec.

Italy’s Lamont Marcell Jacobs, who stormed to victory in the showpiece event in Tokyo, finished fifth.

The race on Monday morning (WA time) was so close, the stadium scoreboard initially flashed a photo finish for the first seven athletes.

The first man to cross the finish line was actually Kerley, whose foot crossed ahead of his chest - the body part which counts.

For perspective, the blink of an eye takes, on average, a tenth of a second, which was 20 times longer than the gap between first and second.

Lyles will start as a resounding favourite in the 200m final later in the week as he looks to match Usain Bolt as the only man to achieve the 100-200 Olympic double this century.

- with AAP