Chicago - Five-time Olympic champion Katie Ledecky won the 800m freestyle on Tuesday at the US Swim Championships with this year's fastest time in the world only 25 minutes after another final.
World record-holder and reigning world and Olympic champion Ledecky, who placed sixth in the 100m freestyle, took the 800m crown in 8:11.50 with Leah Smith, sixth at Rio, taking second, 8.96 seconds back.
Ledecky could swim in four individual events and two relays at next month's World Championships in Budapest, Hungary, with a strong showing at this five-day meet in Indianapolis, Indiana.
"It's important to get the job done here and get to Budapest and do a lot," Ledecky said. "So far I'm setting myself up well but it's just the first day."
While it was a 2017 world best, the winning time was only the ninth-best for Ledecky, who captured 200m, 400m and 800m free Olympic gold last year in Rio - defending the 800m crown she won in London - and helped the US women's 4x200m relay win as well.
Ledecky won the world 400m, 800m and 1 500m freestyle titles and shared in a 4x200m freestyle relay win in 2013 in Barcelona then defended those crowns and adding the 200m world title in 2015 at Russia.
Mallory Comerford, who matched Ledecky for the 200-yard free US college crown, won the women's 100m freestyle in 52.81 seconds, shaving 1.1 seconds off her pre-meet personal best.
Rio Olympic co-champion Simone Manuel was second in 53.05.
Ledecky was sixth in 54.35, matching her seed position. That, combined with the second-best US split time on the Rio 4x100m freestyle relay, should make her a contender to swim the same relay at Budapest.
"All of us want to throw down some good times," Ledecky said. "We want to keep that momentum going from 2016."
Ledecky will swim for world berths and US crowns on Wednesday in the 200m freestyle, on Friday in the 400m freestyle and on Saturday in the 1 500m freestyle.
Nathan Adrian, a five-time Olympic and world champion on relays, out-touched Caeleb Dressel at the wall to win his eighth US title in the men's 100m freestyle in 47.96, edging double Rio relay gold medallist Dressel by 0.01.
Jack Conger, who helped the US 4x200m freestyle relay win Rio Olympic gold, captured the men's 200m butterfly in 1:54.47, beating Pace Clark by 0.11 of a second. Top seed Chase Kalisz, who took Rio 400m individual medley silver, was third in 1:54.79.
Hali Flickinger, who finished seventh at last year's Rio Olympics, claimed her second women's 200m butterfly national crown in 2:07.60, beating Dakota Luther by 1.11 seconds.
True Sweetser, the 2015 US runner-up, won the men's 1 500m freestyle in 14:59.73 with Robert Finke in second, 1.58 seconds back.
Top finishers from Tuesday's finals on the first day of the US Swim Championships at Indianapolis, Indiana, a qualifying meet for next month's World Championships in Budapest (all distances meters):
100m freestyle: 1. Nathan Adrian 47.96 seconds, 2. Caeleb Dressel 47.97, 3. Townley Haas 48.20, 4. Zachary Apple 48.23, 5. Michael Chadwick 48.48, 6. Blake Pieroni 48.49
1 500m freestyle: 1. True Sweetser 14:59.73, 2. Robert Finke 15:01.31, 3. PJ Ransford 15:01.82
200m butterfly: 1. Jack Conger 1:54.47, 2. Pace Clark 1:54.58, 3. Chase Kalisz 1:54.79
100m freestyle: 1. Mallory Comerford 52.81, 2. Simone Manuel 53.05, 3. Lia Neal 53.59, 4. Kelsi Worrell 53.99, 5. Olivia Smoliga 54.31, 6. Katie Ledecky 54.35
800m freestyle: 1. Katie Ledecky 8:11.50, 2. Leah Smith 8:20.46, 3. Hannah Moore 8:27.58
200m butterfly: 1. Hali Flickinger 2:07.60, 2. Dakota Luther 2:08.71, 3. Sarah Gibson 2:08.75