KANSAS CITY, Mo. — Since Simone Biles returned from a one-year hiatus following her triumph at the 2016 Olympics, she has wasted no time trying to reclaim the form that won her four gold medals in Rio.

She has been chasing something greater — a standard that precious few in the world, if any, would dare attempt — by packing an already rigorous floor routine with a skill that no female gymnast has landed, along with adding a riskier dismount on balance beam.

In pushing her skills to the limit, Biles, at 22, is competing against herself. And the results, as she pushes the sport’s boundaries along with them, aren’t always to her satisfaction.

Friday’s first of two nights of competition at the U.S. championships was one such example for the reigning Olympic and world all-around champion, who was forced to put both hands on the mat to avoid falling on the triple-twisting double somersault that will further distinguish her from her rivals.

The rare glitch — she had never done this in practice — dinged her execution score and, worse, irritated Biles beyond belief. But it wasn’t enough to break her spirit. And it certainly wasn’t enough to prevent her from taking the lead in the all-around standings midway through the competition.

“I feel like I compete for perfection,” Biles said afterward, still angry at herself two hours after the unusual mistake, “so whenever I don’t do that, it just really irritates me. To me, I just know I could do better.”

Biles will get another chance to show just that Sunday, when the competition concludes with a repeat performance of all four events. Scores from both nights will be added for the final result.

Biles, who scored the top marks Friday on floor, vault and beam, is heavily favored to win her sixth all-around championship — as is Sam Mikulak, who at the halfway point leads the men’s competition, which concludes Saturday.

Biles, who tallied 58.650 points, has not lost an all-around competition in six years. Sunisa Lee, 16, of St. Paul, Minn., is her closest challenger (56.900). Jade Carey, 19, of Phoenix, stands in third (56.100). Biles’s 2018 world championship teammates Riley McCusker, Morgan Hurd and Grace McCallum are fourth, eighth and tied for ninth.

The lone holdover from the gold medal-winning 2016 Olympic team in the field, Biles was cheered by the crowd of 10,916 before Friday’s competition, and she was greeted by hand-lettered signs and cellphone-snapping fans as she warmed up with the 16 other competitors.

But on floor, it didn’t go according to plan for the reigning Olympic and world champion. Her new skill, a “triple double” in which she packs three twists into two backflips, will be named for her when and if she successfully lands it in a World Cup or at October’s world championships in Stuttgart, Germany. It would be the third skill to bear her name in the sport’s Code of Points, joining another signature skill on floor and a vault.

“Honestly, as soon as I fell on floor, I was like: ‘That’s it! I’m scratching the meet! I’m walking off the floor!’­ ” Biles recounted afterward, managing a smile. “Mistakes will happen. It’s the hardest skill probably in the world. At least I didn’t fall on a double or something.”

Biles’s coach, Laurent Landi, said that he was pleased that Biles was upset because it meant she cared.

“We are pushing the boundaries of gymnastics, pushing her own limitations, and she handled it pretty well,” he said. “It cannot become dangerous, but we are right at the limit.”

Up next was vault, and Biles was in full command, surging to a lead she never surrendered. She weathered the uneven bars, her least favorite event, and stuck the landing with a look of relief. Biles was rock steady on the beam and showed her first unfettered smile of the night after landing the upgraded dismount.

Tom Forster, high performance director for the women’s national team, said there is no precedent for the gains Biles has made since the 2016 Olympics.

“We’re all kind of in awe,” he said. “I’ve been around long enough to know the history of what is going on; no one has ever done that before in [women’s gymnastics] — won the Olympics and come back the next better than the first time. Never been done.

“Her gymnastics has risen; she’s doing more difficult skills and is technically better. Usually they’re trying to hold on [to their skills]. It’s amazing.”