According to Eddie Hearn, promoter for former heavyweight champion Anthony Joshua, the British superstar was excited when he found out Oleksandr Usyk had made a decision to move up in weight.

Usyk makes his heavyweight debut on Saturday night, against Chazz Witherspoon in Chicago.

Last year, Usyk unified the entire cruiserweight division when he united the WBC, WBO, IBF, WBA world titles in the final round of the World Boxing Super Series tournament, as he dominated Murat Gassiev over twelve rounds.

Usyk, due to the WBO's rules, is automatically the mandatory challenger to the WBO strap.

And because of his status, he is in line to fight the winner of the upcoming rematch between Joshua and Andy Ruiz, who battle for the WBO, IBF, IBO, WBA world titles on December 7 in Saudi Arabia.

"Joshua was excited when we signed Usyk, he was excited to see him in the heavyweight division," said Hearn to Sky Sports.

"Joshua saw Usyk a lot in the amateurs and he has never been scared to fight anybody, so he'd be up for fighting Usyk. Usyk is the mandatory but has to keep winning, and has to show that he is ready to fight [the champions] of the division."

But Usyk is not alone, as far as being in line for the Joshua-Ruiz winner, because Kubrat Pulev is the mandatory challenger under the IBF.

"It will be a mess," said Hearn. "The belts are on the line in Saudi Arabia then the winner must decide what to do.

"But there is going to be a problem because mandatories are due with both organisations. He will fight for the world heavyweight title in his next fight, if he beats [Witherspoon]. He wants to jump straight in. He thinks he can beat everybody. We'll never really know until he's in with the elite of the elite. Those four or five guys, big, big men that can really test him.

"I don't know how easily he made cruiserweight, so maybe the extra stone will give him extra power. He won't be the biggest punching heavyweight of all time but whatever he lacks (which won't be much), he will make up for in skill."