TOKYO — The Tokyo Games swim meet commenced Saturday beneath the iconic Olympic rings, with the preliminary heats of the men’s 400-meter individual medley, per tradition, leading things off at Tokyo Aquatics Centre. But nothing else about this opening session of an Olympics in an odd-numbered year felt ordinary.

Day was night and night was day, at least when it came to a flip-flopped schedule in which prelims are taking place in the evening, Tokyo time, and finals the following morning, to satisfy NBC’s demands for a jewel event in prime time back in the United States.

The most important meet of most of these swimmers’ lives, an Olympic Games delayed for a year by a global pandemic, had all the atmosphere of a predawn practice, owing to the absence of fans in the seats. Even an appearance by first lady Jill Biden and the earnest cheers of teammates, socially distanced in the lower bowl, couldn’t fully compensate for that absence.

“Obviously it’s a little different this time, but any Olympic Games is pretty special,” said U.S. breaststroker Andrew Wilson of Bethesda, Md.

As the first U.S. Olympic swim team without Michael Phelps on it since 1996, the first without Ryan Lochte since 2000 and the first without Missy Franklin since 2008, this unit will have forged a new identity by the time this meet ends Aug. 1. None of the biggest American stars — Katie Ledecky, Caeleb Dressel, Simone Manuel, Lilly King, Ryan Murphy — swam Saturday night. But for a team trying to hold off the rival Australians and maintain worldwide dominance, the opening night was a mixed bag.

Though the only true mission in prelims is to advance — and the United States got all 10 of its individual swimmers and its one relay team through to the next round — the Americans secured only three top-three finishes: Chase Kalisz in the men’s 400 IM (third in 4:09.65), Emma Weyant in the women’s 400 IM (first in 4:33.55) and Michael Andrew in the men’s 100 breast (third in 58.62).

In the hotly contested women’s 100 butterfly, Torri Huske, the 18-year-old sensation from Arlington, Va., flirted with world record pace, turning at 50 meters in 25.81, but was outtouched at the wall in her heat by Swedish star Sarah Sjostrom (56.18) — a swim Huske described as “relaxed” — and wound up fourth overall in 56.29, which was plenty good enough to move on to Sunday’s semifinals.

“It’s been really surreal,” Huske, one of 10 teenagers on the U.S. team, said of being in the Olympic Village the past few days waiting for her first swim, “because I’ve felt like the Olympics was always so unattainable, the idea of them. So knowing I’m finally here and I just swam, it didn’t really sink in until right now. It’s been really weird.”

The biggest news of the opening session, at least for the host country, was the failure of Daiya Seto to advance to the final of the 400 IM, an event in which he is the three-time defending world champion and was the clear gold medal favorite in Tokyo. Seto went out strong but appeared to stagger home in the freestyle leg, finishing outside the top eight in ninth place.

The opening session of the Tokyo Olympics may not have been a spectacular day for the United States, but as Seto’s stunning flameout showed, it could have been much worse.