In workouts, Dalilah Muhammad has often been on world-record pace.

On a drizzly Sunday night, she put everything together. Muhammad broke a 16-year-old world record in the 400-meter hurdles by finishing in 52.20 seconds at the U.S. championships.

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Dalilah Muhammad, center, crosses the finish line as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

In workouts, Dalilah Muhammad has often been on world-record pace.

Dalilah Muhammad checks her time after winning the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

With puddles formed on the track, the reigning Olympic champion sloshed her way to eclipse the mark of 52.34 set by Yuliya Pechonkina of Russia on Aug. 8, 2003.

Dalilah Muhammad smiles as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

It was.

Noah Lyles reacts after winning the men's 200-meter dash at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

She lost none of her speed. Then again, the level of the competition brought out the best in her. A world-class field was assembled — even at nationals.

Dalilah Muhammad, center, eyes the finish line as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

McLaughlin finished in 52.88.

Emma Coburn clears a hurdle during the women's 3,000-meter steeplechase at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Later in the night, Dezerea Bryant won the 200 in 22.47 seconds.

Donavan Brazier, right, celebrates as he wins the men's 800-meter run at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

The 22-year-old Lyles can certainly celebrate.

Shelby McEwen reacts after clearing the bar during the men's hight jump at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Shelby McEwen reacts after clearing the bar during the men's hight jump at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

"I'm just shocked," Muhammad said. "I broke the world record."

Dalilah Muhammad, center, crosses the finish line as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Dalilah Muhammad, center, crosses the finish line as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

With puddles formed on the track, the reigning Olympic champion sloshed her way to eclipse the mark of 52.34 set by Yuliya Pechonkina of Russia on Aug. 8, 2003.

Running out of the fourth lane, Muhammad didn't let the rain drops deter her. She looked at her time and was almost taken aback.

No way that can be real, right?

Dalilah Muhammad checks her time after winning the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Dalilah Muhammad checks her time after winning the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

It was.

Muhammad smiled, briefly put her hands on her hips and then slumped down when her time flashed on the screen at Drake Stadium. Third-place finisher Ashley Spencer bounded over to congratulate her as well as teenager Sydney McLaughlin, who hugged Muhammad after finishing second.

To think, Muhammad fell in a training session two weeks ago and suffered a mild concussion. She missed three days of workouts to heal.

Dalilah Muhammad smiles as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Dalilah Muhammad smiles as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

She lost none of her speed. Then again, the level of the competition brought out the best in her. A world-class field was assembled — even at nationals.

Muhammad believes it's not going to last long. It may even fall again at the world championships this fall in Doha, Qatar. Defending world champion Kori Carter didn't even compete at nationals in the event since she has an automatic bye into worlds.

"That 52 is going to get broke," Muhammad said. "If not by me by the other women."

Noah Lyles reacts after winning the men's 200-meter dash at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Noah Lyles reacts after winning the men's 200-meter dash at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

McLaughlin finished in 52.88.

"It was a really fast race and I could feel the pace being pushed," McLaughlin said. "I'm happy to be a part of a world-record race. It's awesome."

Muhammad's performance stole the show.

Dalilah Muhammad, center, eyes the finish line as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Dalilah Muhammad, center, eyes the finish line as she wins the women's 400-meter hurdles at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Later in the night, Dezerea Bryant won the 200 in 22.47 seconds.

"I woke up this morning and I'm like, 'I'm not going to be denied,'" Bryant said. "That was my attitude."

Noah Lyles closed out the competition in style by doing a nifty little dance after taking the men's 200 title in 19.78. He held off Christian Coleman and, after crossing the line, shook his rival's hand before breaking off some dance moves.

Emma Coburn clears a hurdle during the women's 3,000-meter steeplechase at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Emma Coburn clears a hurdle during the women's 3,000-meter steeplechase at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

The 22-year-old Lyles can certainly celebrate.

"Joy? Tons of joy. This is the hardest team to make," said Lyles, who sprayed his hair gray. "The saying is, once you make the U.S. team, you better come away with a medal."

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Donavan Brazier, right, celebrates as he wins the men's 800-meter run at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Donavan Brazier, right, celebrates as he wins the men's 800-meter run at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Shelby McEwen reacts after clearing the bar during the men's hight jump at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)

Shelby McEwen reacts after clearing the bar during the men's hight jump at the U.S. Championships athletics meet, Sunday, July 28, 2019, in Des Moines, Iowa. (AP PhotoCharlie Neibergall)