Olympics fans' jaws dropped over a Katie Ledecky clip that resurfaced from 2020.

At the height of the 'got milk challenge' on TikTok, the Olympics legend jumped on the trend and impressed the masses.

Ledecky placed a glass of chocolate milk on her head and swam the length of an Olympic-sized pool without spilling a drop. 

The clip was reposted by NBC Sports Chicago weeks before Ledecky headed to Paris for the 2024 games, sparking a reaction from fans.

'That's crazy in a good way!! Bravo!!' one user wrote. 'I thought she was going to drink the milk through her snorkel,' another quipped.

'Absolutely amazing... but hey, so is she!' a third commented.

In her book 'Just Add Water: My Swimming Life,' Ledecky explained the thought process behind the viral clip and shared the technique to do it successfully in the first take.

'I climbed in the water and was toying with balancing the drink when it hit me. I should swim the length of the pool with a glass of chocolate milk perched on to of my head,' she wrote.

'I explained to the production team that balancing items on your head is a common drill for backstrokers. It trains them to maintain head position. But I'd never seen anyone do that drill freestyle.'

Ledecky practiced a couple of laps with water before trying it with chocolate milk.

'I made it on my first try! Typically I take thirty eight or nine strokes to get across the pool; for this I counted thirsty six,' she shared. 

'I had to lock my abs to keep my core rigid, so my head remained flat and still. I let my kick do most of the propulsion work. I tried to keep my arms as smooth as butter.

'I don't know if the chocolate milk people realized how crazy the feat was, not being swimming experts. They liked it. But they had no sense of the difficulty. 

'They wanted to shorten the clip. I pushed back. I emphasized to them that we needed to post the entire lap. They conceded. And what do you know? The clip went viral.'

Ledecky's campaign in the French capital has brought her more even success. On Saturday night she won the 800m freestyle to take her tally to 14 Olympic medals.

The Stanford product had already taken bronze in the women's 400m freestyle, followed by a dominant gold in the women's 1500m freestyle and silver in the women's 4x200 freestyle relay.

Other swimmers followed Ledecky after her clip went viral. Australia's Susie O'Neill did it with beer, while American Mark Grevers used nonalcoholic beer.