A super heavyweight title fight between Russian boxer Alexander Povetkin and Haitian-born Canadian Bermane Stiverne that was scheduled for Saturday has been cancelled after Povetkin failed a drug test. Povetkin’s promoter Andrei Ryabinsky wrote on Twitter that the Russian boxer had tested positive for the banned muscle-building substance ostarine. Povetkin was to fight Stiverne for the World Boxing Council (WBC) interim world title in the Russian city of Ekaterinburg.