Russian Maria Paseka, who beat Simone Biles on vault at the 2015 World Championships, is not certain to compete in the Olympics due to a back injury, according to Russian news agency TASS.
Biles is considered a clear favorite for four gold medals -- not done by a female gymnast since Romanian Ecaterina Szabo in 1984 -- and could win five golds -- never done by an American woman or a female gymnast.
Biles captured gold medals at the last two World Championships in the team event, all-around, balance beam and floor exercise.
Vault is her fifth and most questionable event. Biles took silver, silver and bronze on vault at the last three world championships.
Paseka is the only returning vault medalist from the 2012 Olympics (she took bronze) in addition to being the reigning world champion.
Regardless of Paseka, Biles’ primary competition in the vault final may be the 2008 Olympic champion, North Korea’s Hong Un-Jong, who could not compete in London due to North Korea’s ban for age falsification.
Like Biles, Hong earned vault medals at the last three world championships, including gold in 2014.
Biles’ vaults at worlds were less difficult than Paseka and Hong, causing her to lose eight tenths in start value. Biles has since upgraded her weaker vault, increasing her start value.
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