According to the president of the WBO, Paco Valcárcel, if Anthony Joshua wants to remain WBO heavyweight champion, he will have to defend vs. former world cruiserweight champion Oleksandr Usyk (pictured) within the next six months. Of course, Joshua regained the WBA and IBF championships as well as the WBO version when he defeated Andy Ruiz on Saturday so he does have other options if he does not wish to fight Usyk. Also, the IBF may try to enforce its mandatory contender, Kubrat Pulev, on Joshua. Usyk and Joshua are both under contract to Matchroom, while Pulev is with Top Rank, so maybe Joshua will fight Usyk next. So far, Usyk hasn't done much since moving up to heavyweight, only beating a semi-retired Chazz Witherspoon. Matchroom's Eddie Hearn was tight-lipped in his post-fight interview. [Valcarcel tweeted: "Clash of the Dunes is over..now clash of mandatories will be next..WBO mandatory challenger @usykaa with in 180 days].