Caeleb Dressel, of the United States, reacts after winning a heat of the men's 100-meter butterfly at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Charlie Riedel)

Katie Grimes, left, of the United States, talks with teammate Katie Ledecky, following their heat of the women's 800-meter freestyle at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Caeleb Dressel of the United States starts in his heat of the men's 100-meter butterfly at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Adam Peaty of Britain swims in the mixed 4x100-meter medley relay heats at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Kaylee McKeown, of Australia, swims in a heat of the women's 200-meter backstroke at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Martin Meissner)

Caeleb Dressel of the United States swims in a heat of the men's 100-meter butterfly at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Katie Ledecky, of the United States, reacts after winning a heat of the women's 800-meter freestyle at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Charlie Riedel)

Kaylee McKeown of Australia starts in her heat of the women's 200-meter backstroke at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Adam Peaty of Britain starts in the mixed 4x100-meter medley relay heats at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Katie Ledecky of the United States looks up after her heat of the women's 800-meter freestyle at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)