Taylor Ruck almost psyched herself out before the race even started.

Knowing she was swimming against five-time Olympic champion Katie Ledecky in the 200-meter freestyle on Thursday at the Pan Pacific Championships, the Canadian had to calm herself down as she readied to dive into the pool.

"It's the name, I guess, because she is the fastest woman on the planet in a lot of races," Ruck said of the American great. "My coach kind of saw that, so he told me to focus on my lane and my race."

And there's another factor. Almost everyone is already thinking about the 2020 Olympics in Tokyo and using this event as a trial run.

Ruck won the 200 in 1 minute, 54.44 seconds, just ahead of Japanese rival Rikako Ikee. Ledecky was third in 1:55.15. Ledecky won this event two years ago at the Rio de Janeiro Olympics — and the 400 and 800, too — though it probably is her weakest race. She was second in the 200 a year ago at the world championships in Budapest.

It wasn't a lost day. Ledecky took the 800 in 8:09.13 — the fifth fastest on record — and will be the favorite in the 400 during the four-day event in Tokyo, the biggest meet of the year for most swimmers around the Pacific Rim.

"I knew it was going to be tough," Ledecky said. "It's a tough double. I've done it a number of times, but it's always a difficult thing. I really put a lot of work into not having that happen again. But I still have two more years to go until the big show here in Tokyo."

American teammate Lilly King did her thing. The Olympic champion in Rio again won the 100 breaststroke, this time in 1:05.44. Not her best time, but she'll take it.

"I'm just trying to take it year by year, but I do feel it's a little bit of a rehearsal for the Olympics since we're in the same city," King said. "I'm just trying to get used to the culture and things like that. But the Olympics are always in the back of my mind."

King hasn't lost this race since 2015.

"It's definitely my baby," she said. "I don't know how I would take losing, so I'm just trying to keep winning."

Host nation Japan won twice. Yasuhiro Koseki took the men's 100 breaststroke, and Yui Ohashi won the women's 400 individual medley.

Australia's sole victory was in the mixed medley relay. China has sent fewer swimmers and is focusing instead on the Asian Games later this month in Jakarta, Indonesia.

Other American winners included Jordan Wilimovsky in the 1,500, Townley Haas in the 200 freestyle, and Chase Kalisz in the men's 400 individual medley. He beat out Olympic champion Kosuke Hagino and Rio bronze medalist Daiya Seto. Kalisz took silver in Rio.

The Pan Pacs are being held in the Tatsumi International Swimming Center, which will be used for water polo at the next Olympics. A new aquatic center is about 35 percent complete, located just a short walk away.