SIMONE BILES will not defend her Olympic title.

The United States gymnastics superstar withdrew from tomorrow’s all-around competition to focus on her mental well-being.

USA Gymnastics said in a statement that the 24-year-old was opting to not compete.

The decision comes a day after Biles removed herself from the team final following one rotation because she felt she wasn’t mentally ready.

Jade Carey, who finished ninth in qualifying, will take Biles’s place in the all-around.

Carey initially did not qualify because she was the third-ranking US gymnast behind Biles and Sunisa Lee.

International Gymnastics Federation rules limit countries to two athletes per event in the finals.

The organisation said Biles would be evaluated daily before deciding if she will participate in next week’s individual events.

Biles qualified for the finals on all four apparatuses, something she didn’t even do during her five-medal haul in Rio de Janeiro in 2016.

She spent a portion of this evening watching US teammates Sam Mikulak and Brody Malone compete in the men’s all-around finals.

Mikulak, a three-time Olympian, praised Biles’s decision.

“We’ve had some conversations [and] she seems like she’s doing what’s best for her,” Mikulak said.

“It’s awesome to see that she’s gotten to go against the pressure of society and do what’s best for herself.”

The 24-year-old came to Tokyo as possibly the face of the Games following the retirement of swimmer Michael Phelps and sprinter Usain Bolt.

She topped qualifying on Sunday despite piling up mandatory deductions on vault, floor and beam following shaky dismounts.

She posted on social media on Monday that she felt the weight of the world on her shoulders.

The weight became too heavy after vaulting during team finals. She lost herself in mid-air and completed one one-half twists instead of two one-half.

She consulted US team doctor Marcia Faustin before walking off the field of play.

When she returned, she took off her bar grips, hugged teammates Sunisa Lee, Grace McCallum and Jordan Chiles and turned into the team’s head cheerleader as the US claimed silver behind the Russian Olympic Committee.

“Once I came out here [to compete], I was like: ‘No, mental is not there so I just need to let the girls do it and focus on myself’,” Biles said following the medal ceremony.

The decision opens the door wide open for the all-around, a title that was long considered a foregone conclusion.

Rebeca Andrade of Brazil finished second to Biles during qualifying, followed by Lee and Russians Angelina Melnikova and Vladislava Urazova.

The four were separated by three-tenths of a point on Sunday.