Katie Ledeckys teammates are already piling up Olympic medals. Now its her turn, and she wants some hardware of her own.

Ledecky opened her Olympic program as the top qualifier in the 400-meter freestyle on Sunday night, setting up a showdown with Ariarne Titmus of Australia as the American star tries to defend her title.

Ledecky advanced with a time of 4 minutes, 0.45 seconds. Titmus was third-quickest in 4:01.66. The first of their multiple showdowns in Tokyo comes in the final on Monday morning.