TOKYO >> Karsten Warholm of Norway obliterated his own world record in the Olympic 400-meter hurdles Tuesday, finishing in 45.94 seconds to break the old mark by .76.

One of the most anticipated races on the program more than lived up to the hype.

Second-place finisher Rai Benjamin of the United States finished in 46.17, also bettering the 46.7 record that Warholm set just last month.

“Sometimes in training, my coaches keep telling me this could be possible with the perfect race,” Warholm said of the prospect of breaking 46 seconds. “But it was hard to imagine it because it’s a big barrier, and it’s something you don’t even dream about.”

Warholm tore open his jersey when he crossed the line first. He flashed the same mouth-gaping look of amazement as when he announced himself on the world stage with his victory at world championships in 2017.

Benjamin — well, what was there to say?

“If you would’ve told me that I was going to run 46.1 and lose, I would probably beat you up and tell you to get out of my room,” he said. “I’m happy to be part of history.”

Alison dos Santos of Brazil finished third in 46.72; he was among the six runners in the eight-man field to brake either a world, continent or national record.

That included Kyron McMaster of the British Virgin Islands, whose run of 47.08 left him in fourth.

“After the second hurdle. I was like, s—-. If you go after them, it’s suicidal,” McMaster said.

It took until 1948 for a man to run a flat 400 meters under 46 seconds, and the world record in the 400 flat is 43.03. That’s only 2.91 faster than what Warholm did with 10 hurdles in front of him.

“I knew it was possible to do the perfect race at the Olympics,” he said. “But I still can’t believe it. It’s the biggest moment of my life.”

All in all, it was a race that more than lived up to expectations on a steamy afternoon at a mostly empty Olympic Stadium.

Amazing but not unexpected.

The hype for this showdown started building at U.S. Olympic trials in June, when Benjamin became only the fourth man to break 47 seconds with a run of 46.83 and pronounced he thought he had a low-46 in him.

Warholm responded a few weeks later by running the 46.70, and breaking the 29-year-old world record held by American Kevin Young since the Barcelona Olympics.

“I made some mistakes on the backstretch that cost me a little,” Benjamin said, as he held his thumb and his index finger a tiny space apart. “But he’s a great competitor. He runs really fast. You just have to get better.”

Starting in Lane 6, Warholm flew out to the lead, and by the midpoint, he had drawn so far ahead of Benjamin that the real race appeared to be Warholm vs. the clock.

Covering the distance between hurdles 13 powerful steps at a time, Warholm never came close to breaking stride. He sped over the line with arms-a-flailing, but that didn’t cost him much.

Low-46 had been a long-imagined dream for most of these hurdlers. Now, the mark is in the high-45s.

“Forty-seven would’ve been a record, or an Olympic record, four years ago, three years ago, eight years ago, whatever the case is,” said McMaster, the fourth-place finisher. “But 47.08 doesn’t get you a medal” today.

And, this race might have simply been the undercard for the women’s battle Wednesday morning in Tokyo.

Warholm’s record came 24 hours before Americans Sydney McLaughlin and Dalilah Muhammad were scheduled to square off in the women’s 400 hurdle s — a race in which they’ve broken the world record the last three times they’ve squared off in a major competition.