Seven-time Olympic swimming gold medalist Caeleb Dressel was denied again in his bid to return to the World Championships on Thursday, finishing tied for fifth in the 100-meter butterfly at the US championships in Indianapolis.

Dressel, who set the world record in winning 100m fly Olympic gold in Tokyo in 2021, is competing this week in his first major meet since withdrawing from last year's World Championships in Budapest.

Months away from the pool have made a difference this week for the US star, who was 29th in the preliminaries of the 100m free before a third-place finish in the 50m butterfly, an encouraging performance but not enough to make the team for next month's World Championships in Fukuoka, Japan.

In fact, Dressel was ninth-fastest in the 100m fly heats on Thursday but gained a place in the championship final when Ryan Murphy pulled out of the event.

Dressel couldn't capitalize as Dare Rose won in a personal best of 50.74 seconds with 16-year-old Thomas Heilman second in 51.91 seconds.

Heilman, who was second in the 200m fly, became the youngest American male swimmer to qualify for two individual World Championships events as Dressel finished 92-hundredths of a second off the pace.

Dressel, who won the 100m fly, 100m free and 50m free at the Tokyo Games, will have one more shot this week in the 50m freestyle.

He has largely declined to discuss his decision to step away from the pool and his comeback, with coach Anthony Nesty telling broadcaster NBC before the championships that "training-wise, he did a really nice job coming back."

"All we can do is support Caeleb where he's at," Nesty said.

"And he knows where he's at."

In other events Thursday, Torri Huske lined up a defense of the 100m fly world title she won in Budapest with a victory in 56.18 seconds.

Gretchen Walsh was second in 56.34, holding off Kate Douglass whose time of 56.43 saw the race produce the three fastest times in the world this year.

Katie Grimes powered past Alex Walsh on the final freestyle leg to win the 400m individual medley in 4:33.80.

Grimes, runner-up to Summer McIntosh at the World Championships last year, earned another shot at the Canadian world record-holder as she added a pool event in Fukuoka to the open water events she had already qualified for.

Walsh, the reigning 200 IM world champion, also booked a world championship berth with her runner-up finish in 4:35.46.

Carson Foster added a second event to his Fukuoka program, winning the men's 400m medley in 4:08.14, two days after winning the 200m fly.

Chase Kalisz was second in 4:08.22.

Lilly King added a 50m breaststroke win to her 200m breaststroke title. Nic Fink, the 2022 world champion, won the men's 50m breaststroke.

Katherine Berkoff won the women's 50m backstroke and reigning world champion Justin Ress won the men's 50m back.