Minneapolis, Minnesota - Simone Biles looks all but unstoppable as she vies to earn her ticket to Paris at the US Olympic gymnastics trials this week, where competition to fill out the five-woman roster promises to be fierce.

Biles captured her ninth US all-around title earlier this month, winning on all four apparatuses at the US championships in Fort Worth, Texas.

Coach Cecile Landi said Biles's success in managing her mental health combined with sheer talent and a formidable work ethic means the 27-year-old could be better than ever as a third trip to the Olympics beckons.

"I think we always knew she could be better," Landi said Wednesday as women began training at the Target Center in Minneapolis, where the trials start on Thursday with the men's competition.

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"She's the most talented athlete I've ever worked with and so we just knew if she could get her mental game as well as her physical game, then she would be close to unstoppable."

Biles dazzled winning four gold medals at the 2016 Rio de Janeiro Olympics, but her expected star turn at the pandemic-delayed 2021 Tokyo Games was cut short when she withdrew with the "twisties" – a temporary mental block in which gymnasts lose their sense of where they are in the air.

Since returning to competition in August she has gone from strength to strength, piling up more medals including all-around gold at the world championships last year.

The Olympic trials are a nerve-wracking affair – two days of competition each for women and men with the athletes that emerge as the all-around winners having secured their Olympic spots.

A selection committee will then choose the remaining team members, taking into account performances at trials and other competitions including the national championships, as well as what combination of athletes might give the US their best Olympic scoring chances.

The 16 women in the running include Suni Lee, who won all-around gold and uneven bars bronze in Tokyo. She is bouncing back since battling a career-threatening kidney disease.

In her first elite all-around competition since Tokyo, Lee finished fourth at the US championships, shaking off a vault error to win the balance beam where her difficulty score was the highest of any competitor in the event.

Defending Olympic floor champion Jade Carey, a seven-time world medalist, also seeks another trip to the Games as does Jordan Chiles, who helped the US team to silver in Tokyo.