TOKYO — The world’s most dominant gymnastics team, led by the best athlete in this sport’s history, suddenly appears vulnerable. The gold medal at these Olympic Games, once considered all but a sure thing for the United States, now seems in question after the American women, plagued by imprecision all afternoon Sunday, slipped into second during the qualification round. The gymnasts representing the Russian Olympic Committee will enter the team final as the top squad.

This is unfamiliar territory for the U.S. gymnasts, long the standard-bearers in international women’s gymnastics. Russia and China have chased from behind, but since the 2012 Games, the Americans have defeated their peers at the Olympics and world championships by an average of nearly seven points, a monstrous margin in gymnastics. Until Sunday, the United States hadn’t placed second in the qualifying round or in the final since 2010.

The results do not carry over to Tuesday’s final, so Sunday’s mishaps are not detrimental to the team’s gold medal chances. But the scores offered a somber reminder of what could lie ahead. Led by Simone Biles, Team USA earned a 170.562 during the opening day of competition, a full point behind the Russians, who led the field with a 171.629.

“Mentally, they’re going to be okay,” U.S. high performance director Tom Forster said. “This is not the finals. This is getting into the finals, so this might be a great awakening for us.”

Perhaps what’s most concerning is that the United States wasn’t undermined by a single disastrous routine. Instead, persistent miscues culminated in an underwhelming outing. And the result is just as much a product of the Russians’ fantastic showing. The Russian Olympic Committee has a deep team that showcased its progress since it last faced the Americans at a major competition.

For years, Biles has offered Team USA a major cushion because her scores so far exceed those of her peers. That usually gives the Americans room for error. Biles had the best all-around score here with a 57.731 and could start racking up gold medals this week.

During her debut in Tokyo, Biles had a few errors: She bounced out of control with too much power on a tumbling pass. As she flipped off the vaulting table, she veered to the side and needed to step off the mat. When she dismounted off the beam, she stumbled a few steps backward, a mishap that Forster said he had never seen before.

Beyond that, Biles avoided major trouble. She still advanced to the final on each apparatus. U.S. teammate Sunisa Lee, who also will compete in the all-around final, landed in third with a 57.166 behind Biles and Brazil’s Rebeca Andrade. But then the Russian Olympic Committee had the next three best all-arounders, a testament to its depth.

Lee performed her trademark standout bars routine, earning a 15.200, the second-highest score in Sunday’s competition. Lee’s routine is packed with connections of difficult release moves, and she could earn a gold medal on the only apparatus on which Biles isn’t in the mix to win. Lee also recorded Team USA’s best score on the beam (14.200) and advanced to that final.

The U.S. women never fully rebounded after a nervy start on the floor. In addition to Biles’s error, Grace McCallum opened the competition with a bounce out of bounds, and Lee landed short on her final tumbling pass. Jordan Chiles has epitomized consistency this season, hitting every routine in her past four competitions. But on Sunday, she dragged her feet on the ground after a transition down to the low bar. She fell twice on the beam, ending a performance that Forster admitted was “surprising.” All six of the U.S. gymnasts declined interviews after the competition.

“Just like in any other sport, great athletes drop the ball in the end zone or a quarterback throws an interception,” Forster said. “It happens.”

Apart from Biles, these are all first-time Olympians, so Forster doesn’t think any sense of overconfidence crept into the gymnasts’ minds. And this could turn into a blip that fades from memory after an outstanding performance in the final.

Within the U.S. team, gymnasts battled for spots in the finals because just two athletes per country can qualify for each one. Jade Carey, who’s here as an individual and doesn’t contribute to the team total, dealt with a minor injury this season and hadn’t performed her full difficulty before arriving in Tokyo. But she peaked at the right time and qualified for the finals on the vault and floor.

Carey had a strong floor routine with controlled landings on her difficult tumbling passes and then delivered two excellent vaults. She finished narrowly behind Biles on both apparatuses. Fellow American MyKayla Skinner, also in Tokyo as an individual, placed fourth on the vault. She would be a medal contender in that event, but the rule limiting the number of competitors per country left her on the outside.

When the gymnasts return to Ariake Gymnastics Centre, medals will be at stake — first in the team and all-around competitions, then on each apparatus. The errors that appeared during the qualification round could become costly. After naming the U.S. Olympic team, Forster said, “We’re so, so fortunate that our athletes are so strong that I don’t think it’s going to come down to tenths of a point in Tokyo.”

But at least based on Sunday’s performance, that’s not the reality anymore.