By Steve Keating

SAN JOSE, California (Reuters) - In a nod to the domination of her sport, Simone Biles has already entered the debate as the greatest gymnast of all-time even though she has yet to turn a single somersault on the Olympic stage.

A charismatic dynamo blessed with otherworldly talent, Biles may be the three-time reigning all-around world champion but for gymnasts it is the Olympics where true greatness is defined.

Having dealt with the formality of securing a spot on the Rio-bound U.S. team with another dominating display at the national Olympic trials on the weekend, Biles is not just poised to put her stamp on gymnastics but the entire Summer Games.

"She's the best in the world and she will be the best gymnast that has ever lived in my opinion," said Nastia Luikin, the 2008 Olympic all-around gold medalist. "All that is missing is that Olympic gold, that is the cherry on top. But I have no doubt in my mind she will do that.

"I guess I'm just glad I'm not competing anymore."

Nadia Comaneci, Olga Korbut and Mary Lou Retton are the sport's transcendent names and Biles could soon join them with an ambitious Rio Games plan that could see her challenge for five gold medals.

She will arrive in Rio as the red-hot favorite for the coveted all-around crown and to lead the U.S. defense of

the prestigious team title.

More gold awaits on the individual apparatus, balance beam, vault and floor, where she is expected to whip up the Brazilian crowd with a saucy, high-flying routine played out to a Latin beat.

"She's a machine," said Retton, who broke the Eastern European grip on the all-around title when she took gold at the Soviet boycotted 1984 Los Angeles Olympic. "She should have to compete with the guys, she is so good. She pushes it. She's the best gymnast I have every seen in my lifetime.

"She's going to have that Olympic title; she just has to show up. It's hers."

Currently there is no one out there capable of standing up to the 4-foot, nine-inch African American powerhouse.

The 19-year-old competes with joy and ruthless, clinical efficiency.

In a sport that routinely sees champions crowned by fractions of a point, Biles's margin of victory is often two, three or even four points.

She does not beat the competition she crushes it, all with a disarming smile on her face.

"She is that good, she is so impressive," Shannon Miller, a twice all-around world champion and double Olympic gold medalist at the 1996 Olympics. "In gymnastics it is so difficult to stay on top ... she'll win by four points, it is absolutely incredible.

"Honestly I cannot think of anyone who has separated themselves as much from the pack as Simone.

"It really is something we have never seen before."

Biles is the complete gymnast with an unmatched arsenal of skills. She possesses explosive power and a killer instinct but balances that with off-the-charts charisma and a genuine playfulness.

It all adds up to an unbeatable combination.

"She has the tangible and the intangible, she has the technique, the difficulty level, the artistry she is able to put into routines in these days," Miller told Reuters. "She's got the consistency; I think I've only seen her fall once and that was a fluke.

"But when you watch her compete she has this infectious smile and attitude, everyone loves her."

When the Games open on Aug. 5 Usain Bolt and Michael Phelps will be the undisputed headliners but when the Olympic flame is extinguished on Aug. 21 it could be Biles leaving Brazil as the newest Olympic darling.

Once every four years a gymnast tumbles and twists her way into the hearts of a worldwide viewing audience.

At the 2008 Beijing Olympics it was the elegant Luikin, in London it was Gabby Douglas and now the red carpet has been rolled out for Biles, who lands in Rio a relative unknown but is poised to return home a global sporting sensation.

Biles, however, deflects any notion of greatness, adding humble to her list of special qualities.

"We're just trying to carry the legacy on," said Biles, turning the focus onto her team mates. "Yes I have accomplished so much and I should be grateful but it is not like walk around, 'I'm three-time world champion.'

"It's something you should feel blessed you have the opportunity to do, it is just a label at the end of the


While Biles is desperate not to be labeled she might soon have two more on her resume -- Olympic champion and greatest of all-time.

(Editing by Frank Pingue)