Simone Biles' return to action is bound to ensure a dramatic conclusion to the Tokyo Olympics gymnastic competition on Tuesday as the American bids to end her Games with gold in the balance beam final.
American Biles arrived in Tokyo ahead of the Games with designs on a record haul of six gold medals that would have made her the greatest ever Olympian but her Tokyo experience turned tumultuous from the get go.
After dropping out of last week's team event after one vault, the 24-year-old pulled out of the all-around final and three of the four apparatus finals - the floor, vault and uneven bars.
The four-time Olympic champion cited mental health issues for her abrupt withdrawal from the team event - in which the USA picked up a silver medal - and and that she was dealing with the "twisties" - where gymnasts are disoriented during their gravity-defying sequences.
While Biles is the reigning three-time world champion on the beam and 2016 Rio bronze medallists it is not considered her best apparatus.
But it does represent the least risk when it comes to skills that might be impacted by "the twisties".
A number of difficult acrobatic skills have to be performed on the beam but fast-paced tumbling and aerial twisting manoeuvres are limited on the apparatus.
If Biles were on top of her game she would be the clear favourite, but questions about her fitness and state-of-mind hang in the air leaving the competition wide open.
