Simone Biles left the world stunned after she withdrew from the all-around final at the Olympics on Thursday. The reigning Olympic and five-time world all-around champion cited mental health issues for pulling out of the 2021 Summer Games."I have to focus on my mental health. I didn't want to go out and do something stupid and get hurt... At the end of the day we don't want to be carried out of there on a stretcher," Simone Biles was quoted by AFP as saying.The decision marks a shocking turn of events for the US gymnast and for her team. Simone Biles was widely expected to crown the greatest career in gymnastics history with another multiple gold medal haul in Tokyo.READ: Windy conditions halts Indian rowing team from conquering new frontiers at Tokyo Olympic GamesCheck Out: Tokyo Olympics 2021 ScheduleThe diminutive athlete is the winner of four Olympic titles and was vying for a potential total of six gold medals in Tokyo.so incredibly proud of this girl right here 🤍thanks for always keeping gym light hearted and fun! love you! you’re amazing ms olympian 🤩 @mykaylaskinner pic.twitter.com/xSd3PAJCNn— Simone Biles (@Simone_Biles) July 25, 2021However, she decided to withdraw after an uncharacteristically shaky performance in the vault. This leaves a spot for the United States Artistic Gymnastics Federation to fill in before Thursday's final.Check Out: Tokyo Olympics 2021 ScheduleWho will replace Simone Biles?Jade Carey will replace Simone Biles in the Olympics women’s gymnastics all-round final.READ: Can Manu Bhaker make mends in 25m air pistol event after two disappointing lossesCarey finished ninth in all-round in women’s qualifying, competing as an individual and not as part of the US team. She did not qualify initially as she was ranked third behind Biles and Sunisa Lee. As per the International Gymnastics Federation (IGF), a country can field up to two athletes per event in the finals.The 21-year-old had already qualified for the vaulting and floor exercise finals, slated for August 1 and 2 respectively.GO TEAM USA 🇺🇸 pic.twitter.com/A8rnCgciLI— Simone Biles (@Simone_Biles) July 22, 2021She qualified for Tokyo through the Apparatus World Cup Series (2018-20), leading on the floor and vault in that process.The youngster was allowed to participate in all-around qualifying, where she scored high enough on balance beam – apart from floor and vault – to be finish third amongst US gymnasts.Never underestimate how strong you are 💪 New episode of Simone vs Herself is out now! I hope you guys like it. Click the link below to watch Simone vs Herself (@vsonwatch) only on @facebookwatch. #SimoneVsHerselfhttps://t.co/GUtEEaxcrx pic.twitter.com/l0hAO5LK45— Simone Biles (@Simone_Biles) July 13, 2021Simone Biles was first in all-around qualifying despite a rough performance followed by Brazil's Rebeca Andrade and Lee.READ: "Not everything is in our hands" - Saurabh Chaudhary reacts to losing in 10m air pistol mixed event