Gymnast superstar Simone Biles is on the eve of returning to the competition floor in suburban Chicago, two years after the "twisties" forced her to withdraw from team finals at the Tokyo Olympics.

Biles, a seven-time Olympic and 25-time world medallist, showed off routines on all four apparatus in podium training on Friday ahead of Saturday's US Classic in Hoffman Estates, Illinois.

The 26-year-old looked as sharp as ever and completely free of the twisties, the terrifying experience where gymnasts are separated from their sense of spatial awareness.

Biles had dropped that hint on her Instagram stories last weekend, saying "I'm fine. I'm twisting again. No worries. All is good."

The 2016 Olympic all-around champion took more than a year off training after the Tokyo Games, but her routines show no signs of a slowdown.

"She looks amazing," fellow Tokyo teammate and Tokyo Olympics all-around champion Sunisa Lee said of Biles after Friday's training session.

"It doesn't even look like she took any time off."

Biles informed her coaches earlier this year of her intent to return, and they were optimistic on her prospects after training on Friday.

"We wouldn't be here if we had seen any hesitation," said Cecile Landi, who along with her husband Laurent coaches Biles in Texas.

At US National Team Camp last month, Biles performed with similar skill difficulty as her Tokyo repertoire, besting the competition in the all-around by a massive margin of 3.5 points.

That included a Yurchenko double-piked vault, a skill so challenging that it has never been attempted in competition by another female gymnast.

Biles warmed up that vault on Friday, but if she eventually brings it to the world stage, it will mark her second namesake vault in the international code of points.

Biles is the most decorated gymnast at Saturday's two-session competition, but the women's line-up is stacked, sharing a combined 55 Olympic and world medals according to gymnastics podcast Gymcastic.

Along with Biles and Lee, other notable competitors include 2020 Olympic floor exercise champion Jade Carey, 2020 Olympic team silver medallist Jordan Chiles, and Leanne Wong, 2021 world all-around runner-up.