Taylor Ruck of Scottsdale opened at the Pan Pacific Swimming Championships with a gold-medal swim and win over American Katie Ledecky.
Ruck, 18, who trains in Toronto, won the 200-meter freestyle in Tokyo in 1:54.44 (fastest in the world this year), ahead of Japan's Rikako Ikee (1:54.85) and Ledecky (1:55.15).
Ledecky won the 800 free before swimming in the 200. She is the world record holder in 400, 800 and 1,500 freestyle.
Ledecky recently turned professional after swimming two years at Stanford, where Ruck will begin her college career this fall.
Allison Schmitt, who trains with Pitchfork Aquatics in Tempe, was fourth in the 200 free in 1:56.