INDIANAPOLIS -- Even before the Americans' world championship swimming roster was complete Saturday night, Natalie Coughlin and Nathan Adrian looked around and realized things were going to be different in Barcelona.
Cullen Jones and Allison Schmitt didn't make the team. Rebecca Soni is taking a year off. Michael Phelps has retired, and some of last summer's Olympic gold medalists who are competing, such as Ryan Lochte and Matt Grevers, are not back to world-class shape.
So the next generation of swimming stars took advantage to make a splash at this week's U.S. national championships, changing the face of the American team.
"It's crazy talking with a lot of the other swimmers and seeing so many new faces," said Coughlin, a three-time Olympian who will swim the 50-meter freestyle in Barcelona. "That's great for the sport, but you miss some of your friends. I'm looking forward to seeing some new faces."
There are plenty of new ones and young ones, though not necessarily both.
The women will be led by two teenage stars who dominated the headlines in Indianapolis: 18-year-old Missy Franklin and 16-year-old Katie Ledecky.
In London, the enthusiastic Franklin became a breakout winner, taking home five medals, four of them gold. Ledecky, the Americans' top distance swimmer, has expanded her repertoire and is now positioned to improve on the one gold medal she won in London.
While neither has yet started college, each clearly is becoming a cornerstone for the Americans' future.
Franklin qualified in four individual events in Indy -- the 100 and 200 free and the 100 and 200 backstroke -- by posting times that ranked among this year's top five in the world in each event.
Ledecky's ambitious schedule at nationals included the 200, 400, 800 and 1,500 free. She qualified in all four, potentially setting up a head-to-head showdown with Franklin in the 200 free. The two also are likely to form the nucleus of multiple U.S. relay teams.
If Ledecky does compete in the four longest freestyle events at worlds, she would become the first American woman to achieve the feat. Shirley Babashoff came closest, competing in the 200, 400 and 800 in the 1975 worlds and 1976 Olympics -- long before the 1,500 was added to the women's schedule.
"I guess it's not something I think about. I just want to come along and do the best I can in every event," Ledecky said. "I'm really excited about being in the relay ..."
Ledecky's not the only one trying something new.
Coughlin, now the oldest swimmer on the women's world team at 30, will chase a world title in the 50 free for only the second time in her career. She finished eighth in the event in 2007.
But the youngsters are now beginning the traditional transformation in a post-Olympic year.
Of the 24 women on the U.S. roster, seven are teens and 15 are age 21 or younger. The list includes everyone from Franklin and Ledecky to 15-year-old open water contender Becca Mann and 16-year-old Simone Manuel, who qualified in the 50 free and 400 free relay. Manuel came within an eyelash of beating Coughlin in the 50 free and broke the national age group record in that event twice Saturday, a mark Franklin held for two years.
The men are undergoing a similar transition.
While the 25-member men's roster includes familiar names such as Tyler Clary, Grevers and Lochte, many 2012 Olympians acknowledge they took some time off and are just now working their way back into shape.
Clary said he gained about 30 pounds during a three-month respite following the London Games, and Grevers took a break to get married. Even Lochte, the biggest name on the men's side, acknowledged Saturday night he must pick up the pace of his training.
"I wish I had started back a little earlier than I did," Lochte said after winning his signature event, the 200 individual medley, in a less than spectacular 1:55.44. "I promise I'll be more committed in the next couple of years. If I am going to get back to the level that I know I'm capable of doing, I have to go back to work."
Starting now. Lochte said he plans to spend about 10 days in hard training for the worlds and then will begin to taper for what he hopes will be a better showing in Barcelona.
Like the women, the young men are taking advantage of their opportunities.
Eleven swimmers on the men's team won't turn 23 until after the worlds, including five teens, and a dozen have never competed in an Olympics.
It's a completely new look for a team that has relied on international veterans such as Brendan Hansen, Aaron Peirsol, and, of course, Phelps to pave the way over the last decade.
The 28-year-old Lochte and 24-year-old Adrian will now fill those veteran roles, though they both know this will be a very different kind of world championships for their teammates.
"There's a lot of new faces, a lot of veterans gone. It's sad leaving a guy like Cullen Jones behind because I think he has a lot more to offer us than just swimming," Adrian said before discussing the absence of Phelps. "It's going to feel very strange, and it's tough. I think the entire team drew a lot strength from Michael, even in an off-year because of how good he is and how consistent he is. It's going to be hard to replace him in the relays, but fortunately, we have Eugene (Godsoe) in the 100 fly."