OMAHA, Neb. — The United States is assembling an Olympic swimming team that Michael Phelps hardly recognizes.

Nearly halfway through the eight-day trials, the team bound for Rio de Janeiro next month has as many as 17 first-timers. Left in their wake so far are such stalwarts as Missy Franklin, Natalie Coughlin, Matt Grevers, Tyler Clary and Jessica Hardy.

Phelps, who turns 31 on Friday, and teenager Katie Ledecky appear to be the only sure things at a meet described by Phelps as more pressure-packed than the Olympics. “It’s harder here,” he said.

No one is finding it tougher than Franklin.

Four years ago, she was a bubbly teenager who became a star at the London Games, winning five medals, including four golds. Now, she’s a professional athlete, albeit still oozing charisma, and sponsors are betting big bucks on her to succeed again. But Franklin won’t be defending her gold medal in the 100-meter backstroke after finishing a stunning seventh in the final Tuesday night.

“Right now I need to make the team in whatever way that looks like,” she said.

It might only be on a relay.

Franklin’s next chance comes Wednesday night in the 200 freestyle, where she’s a longshot. Katie Ledecky, already on the team in the 400 free, looks to lock up a second event. She goes into the final more than a second faster than everyone else, leaving Franklin and defending Olympic champion Allison Schmitt among those scrapping for second.

“That’s a tough one,” Franklin said.

The top six finishers in the 200 free can make the team and be potential relay swimmers. Franklin and Schmitt would rather finish first or second so they could swim the individual event in Rio. But simply making the team would be enough at this point. Schmitt also won five medals in London, but has yet to impress in Omaha. She was fifth in the 400 free.

“She’ll be able to work through some of the things she needs to work through,” Phelps said of his longtime friend Schmitt.

Phelps is expected to make his fifth and last Olympic team Wednesday night in the 200 butterfly final. He qualified with a time that is 1.10 seconds faster than anyone else. His protege, Chase Kalisz, will try to grab the second spot. Kalisz made his first Olympic team in the 400 individual medley.

“I see a lot of new faces. I don’t even know half of them,” Phelps said. “It’s exciting to have new faces, where people are really pumped to come up in the sport. That’s a good thing to see as I’m on my way out.”

Ryan Lochte, Phelps’ rival and friend, eked onto the team Tuesday night with a fourth-place finish in the 200 free. Lochte is competing hurt, having injured his groin in the 400 IM preliminaries last Sunday.

“You can never go in knowing that you’re going to make the team, just because the U.S. is one of the hardest countries to make the Olympic team for because they’re so strong in every event,” he said. “You’ve just got to hope and believe that you can.”

Franklin isn’t the only American who won’t be defending an Olympic title in Rio.

Matt Grevers, the 100 back champion four years ago, finished third in the final, beaten a half-second by first-timers Ryan Murphy and David Plummer, a 30-year-old father.

“I’m a little stunned,” Grevers said. “After I let it sink in, I’ll be more distraught than I currently am.”

He has another shot Wednesday in the 100 free preliminaries, needing a top-six finish to be considered for a relay berth.