Katie Ledecky began USA Swimming Nationals in Irvine, Calif., in much the same way she did last year’s meet — by winning another championship.

The four-time world champion won the women’s 800-meter freestyle in 8 minutes 18.47 seconds, her third straight title in the event and her fifth overall since first winning gold at the 2012 London Olympics.

It wasn’t the swim many expected of Ledecky, who broke her own world record in the event at a tune-up meet in June. That is the price of success in swimming, where the expectation of world record holders is more world records.

By winning, she qualified for the U.S. delegation to the Pan Pacific Championships, Aug. 21-25 in Gold Coast, Australia.

Ledecky, a rising senior at Stone Ridge School of the Sacred Heart, attacked Wednesday’s race from the start, as she has done in every other American or world record-breaking swim. At the 300-meter mark, she was one second under the world record time.

That’s when the grueling hours spent in the pool over the past few months began to creep into the 17-year-old’s arms and legs.

By the 600-meter turn, she was more than two seconds off the record pace.

Ledecky said after the race that the goal entering the meet was to make the Pan Pacific team. Ledecky has spent the summer months focused on her training, which began with an 18-day trip to the Olympic Training center in Colorado Springs, Colo.

It was on the way back from Colorado that Ledecky broke two world records at a meet outside of Houston.

She is scheduled to swim six more events at nationals, including the 1,500 freestyle, an event in which she also holds the world record.

Andrew Gemmell, Ledecky’s summer training partner and son of Coach Bruce Gemmell, won the men’s 1,500 freestyle in 15:07.82. He had already qualified for Pac Pacs by winning the 10-kilometer open water event in June.

Elsewhere at the meet, Michael Phelps had an inauspicious start in the first of his four events. The most decorated Olympian in history, who ended an 18-month retirement in April, finished seventh in the men’s 100 freestyle. Olympic champion Nathan Adrian won the event in 48.31 seconds. Ryan Lochte was second, followed by Jimmy Feigen.

Seven of the eight swimmers in the heat were Olympic medalists; the other six all beat Phelps.

“It’s about qualifying. In a field like that it’s always an honor to get your hand on the wall first,” Adrian said. “You work all year with a certain race strategy in mind, and you’re really going to do your best to execute it.”

Up next for Phelps is the 100 butterfly on Friday, an event in which he’s won three-straight gold medals.

Jack Conger, a three-time All-Met Swimmer of the Year at Good Counsel, won the ‘B’ final in a personal-best 49.28 seconds.

Missy Franklin won the women’s 100 freestyle in record time, closing like a freight train in the final 30 meters.

Her time of 53.43 was a U.S. nationals meet record and ranks the 19-year-old California swimmer fifth in the world this year. Eighteen-year-old Simone Manuel, the American record holder in the 100-yard distance and future Stanford swimmer, finished second in 53.66.

“I knew that Simone was right next to me and she always goes out so fast,” Franklin said. “I knew I was going to have to come home hard so I just put my head down and tried to get my hand on the wall.”

Tom Shields won the men’s 200 butterfly in 1:55.09 with a heroic swim from the front that left the field racing to catch up over the final 150 meters. All-Met Swimmer of the Year Andrew Seliskar finished fourth overall in 1:56.65.

Cammile Adams won the women’s 200 butterfly in a time of 2:07.12. Cassidy Bayer, a rising West Potomac High freshman, finished eighth in the heat in 2:12.30. She was slightly better during prelims at 2:11.88. It was the 14-year-old’s first-ever championship final.