The 2016 All-around champion in rhythmic gymnastics shares why she believes ROC will win gold and silver at the Tokyo 2020 Games. Seven-time world champ... Margarita Mamun believes the 'complexity' of the Averina twins' elements will see them dominate the Olympic events, but what does she believe are the differences between Dina and Arina, and hear her thoughts on fellow Rio champ Simone Biles in this exclusive interview.