Swim showdown: US star Ledecky, Aussie to battle for gold
Australia's Ariarne Titmus competes in a 400-meter freestyle heat at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo. (AP Photo/David J. Phillip)

Australia's Ariarne Titmus competes in a 400-meter freestyle heat at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo. (AP Photo/David J. Phillip)

Jul. 25, 2021 07:50 AM EDT
Katie Ledecky, of the United States, reacts following her heat of the women's 400-meter freestyle at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Katie Ledecky, of the United States, reacts following her heat of the women's 400-meter freestyle at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Jul. 25, 2021 07:38 AM EDT
Katie Ledecky, of the United States, swims in a heat during the women's 400-meter freestyle at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Katie Ledecky, of the United States, swims in a heat during the women's 400-meter freestyle at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Jul. 25, 2021 07:38 AM EDT
Yuliya Efimova of the Russian Olympic Committee swims in a heat during the women's 100-meter breaststroke at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Martin Meissner)

Yuliya Efimova of the Russian Olympic Committee swims in a heat during the women's 100-meter breaststroke at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Martin Meissner)

Jul. 25, 2021 06:57 AM EDT
Tatjana Schoenmaker, of South Africa, swims in a heat during the women's 100-meter breaststroke at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Charlie Riedel)

Tatjana Schoenmaker, of South Africa, swims in a heat during the women's 100-meter breaststroke at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Charlie Riedel)

Jul. 25, 2021 06:58 AM EDT
Katie Ledecky of the United States leaves the pool following heat during the women's 400-meter freestyle at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Martin Meissner)

Katie Ledecky of the United States leaves the pool following heat during the women's 400-meter freestyle at the 2020 Summer Olympics, Sunday, July 25, 2021, in Tokyo, Japan. (AP Photo/Martin Meissner)

Jul. 25, 2021 07:43 AM EDT