TOKYO—The road to a third-straight Olympic gold medal for the Simone Biles-led U.S. women’s gymnastics team will not be the coronation everyone has been expecting. 

The heavily favored U.S. team finished their qualifying round behind Russian athletes on Sunday, showing that they could possibly slip from the sky-high pedestal built for them by the decadelong dominance of the American gymnastics program and the hype surrounding Biles, its superstar.

The squad is still assured a spot in the team final scheduled for Tuesday. And Biles— undefeated in national, world and Olympic all-around competition since 2013—stood atop the individual standings as competition continued late Sunday, with likely qualification for floor and vault finals as well. Her spot in the balance beam final was less certain.

Biles had an uncharacteristic number of significant errors. She flew out of bounds and off the mat entirely on her third tumbling pass in the floor exercise, took another big step out of bounds on her Cheng vault, and staggered backward on her dismount from the balance beam.

The missteps she and other U.S. team members made during qualification, combined with the unexpectedly strong performances from the Russians, suggests a far more closely fought final than had been anticipated by many. 

“We hope that we’re also going to struggle and fight. We have to. That’s the expectation for us,” said Angelina Melnikova, the top gymnast on the team competing under the name of the Russian Olympic Committee, after they finished their qualifying division Sunday. Russia is barred from competing as a country after being found guilty of operating a state-sponsored doping program.

Biles has additional difficult skills that she held back during qualifications, including the hardest vault in the history of women’s gymnastics, the Yurchenko double pike, and a harder, double-twisting double somersault beam dismount. More frequently, any struggles from Biles have come after an outstanding first-day performance, meaning that shaking out some jitters early on could boost her later.

‘We hope that we’re also going to struggle and fight,’ said Russian gymnast Angelina Melnikova. ‘We have to. That’s the expectation for us.’

‘We hope that we’re also going to struggle and fight,’ said Russian gymnast Angelina Melnikova. ‘We have to. That’s the expectation for us.’

Photo: lionel bonaventure/Agence France-Presse/Getty Images

The U.S. women walked past reporters after their division was over without taking questions. The team high-performance director Tom Forster, however, talked at length about what had happened, attributing many of the problems to mental errors that he believed were fixable.

“It’s just the nerves of being in competition,” he said. “Mentally we’re going to be OK. It’s just about being focused. And it’s good. I mean, this was not the finals. This was about getting into the finals. So this might be a great awakening for us and we’ll take advantage of it.”

Forster still felt good about a decision to pick the top four all-around finishers at Olympic trials after years of controversies around the makeup of the team, rather than strategizing differently. He also said that he has seen greater depth in the Russian gymnastics program emerging in recent years, and acknowledged that their performances were the cleaner ones on Sunday. 

The Russian Olympic Committee’s team includes two 16-year-olds with breakout showings, Viktoriia Listunova and Vladislava Urazova. 

Listunova’s appearance here was only possible because of the pandemic-induced one-year delay to the Games. She didn’t meet the minimum age requirement to compete at the senior level in 2020; the international gymnastics federation allowed 2005-born athletes to compete at the Games after they were moved to 2021.

The U.S. team has been on a rollercoaster since touching down in Japan. A vaccinated alternate, Kara Eaker, tested positive for the novel coronavirus during a pre-Games training camp and quarantined, and another alternate, Leanne Wong, was also placed into isolation. The designated competitors were allowed to proceed to Tokyo but team officials had clearly been unnerved by the experience.

American gymnastics more broadly has also been rocked by scandals throughout the past five years, both around the prolific sexual assaults perpetrated by former national team doctor Larry Nassar and USA Gymnastics’ handling of it, the departure of top administrators and sponsors, and then a larger reckoning with the sport’s culture, and physical and emotional abuse within it.

Sunisa Lee finished qualifications on track to join Biles in the individual all-around competition and leading the field in uneven bars. Jade Carey, competing as an individual rather than a member of the four-woman U.S. squad, is set to appear in the floor and vault finals along with Biles. 

Write to Louise Radnofsky at louise.radnofsky@wsj.com