Karsten Warholm revelled in the "wow" factor of his astonishing 400 metres hurdles triumph as the world record was obliterated at the Tokyo Olympics.

The 25-year-old Norwegian ran 45.94 seconds, breaking the record for a second time in five weeks, after Kevin Young previously held the global mark for 29 years.

"I didn't touch one hurdle. I was even able to find another gear coming home, so 'wow'," Warholm said.

"It's just so big. It's almost like history here. It was the only thing missing from my collection. I had a World Championships [gold medal]. I had European Championships, I had the world record, the European record.

"The Olympic gold medal is what everybody talks about. I knew this race was going to be the toughest of my life, but I was ready."

The top three in the race all went under 47 seconds and beat the previous Olympic record, with silver for American Rai Benjamin in 46.17 and bronze going to Brazilian Alison dos Santos in 46.72.

Karsten Warholm

Warholm ran 46.70 in Oslo at the start of July to slash 0.08 seconds off Young's long-standing record, which was set at the Barcelona Olympics.

There were many ways to dissect the magnitude of this latest record, and one was to look at how the world record shifted by just 0.75 seconds from Ed Moses running 47.45 in 1977 until Warholm's 46.70 in July.

To now scythe a further 0.76 seconds off the all-time mark represented a staggering achievement.

"I mean, man it’s so crazy. It’s by far the biggest moment of my life," Warholm said.

"It defines everything, all the hours I put in, everything that my coach has been working for.

"I dream about it like a maniac, I tell you. I sleep all night on it. I spend all my time thinking about this, so just getting this last medal into my collection, it’s complete.

"I can't sleep. I've spent thousands of hours thinking about this.

"I had this special feeling in my chest, you know when you are nervous. I was just thinking this is the feeling that I had when I was six years old. I've never had that feeling since I got older, but yesterday I had it."

Warholm had a healthy lead heading into the final 150 metres but came under pressure from Benjamin over the final two barriers, the gap closing.

The 25-year-old from Ulsteinvik held his nerve and maintained his rhythm, though, sprinting away to post a record that could stand for many years to come.

Some even compared it to Bob Beamon's 1968 long jump world record in Mexico City, which stood for 23 years and remains the second longest leap of all time.

Benjamin was reduced to tears after the race, having delivered the performance of his life but still finished on the second step of the podium

"Knowing that you want to be the best, this is what it costs. It's hard. It hurts. But it is what it is," Benjamin said.

"I always give myself 24 hours to process things. Right now I am just full of emotion. I have worked so hard. This is what matters. I got a medal but it just hurts to lose."

He added: "I'm a dog. I'm a fighter. It's my first Olympics. I made some mistakes that cost me, but it's all right. I'll fix it."