Anthony Joshua

Hearn confirmed on Saturday night that Joshua had triggered his rematch clause against the Ukrainian.

Usyk stunned Britain's Joshua last month, winning by unanimous decision to take the WBA, IBF and WBO heavyweight belts.

"He [Joshua] has got his head back in the game," Hearn said.

"He is training now and today we officially triggered the rematch for the Oleksandr Usyk fight which we will see early next spring.

"We're looking for him to become a three-time heavyweight world champion. I think realistically March is when you're likely to see the rematch."

The 34-year-old former undisputed cruiserweight world champion put on a masterclass to silence the majority of the 67,000 fans inside the huge arena on Sunday (NZ time).

Usyk proved too elusive for Joshua throughout an enthralling contest and finished with a flurry in round 12 as he went in search of a knockout.

Joshua stayed up but the decision was a formality as Usyk claimed the WBA, WBO, IBF and IBO belts.

The WBA (Super), WBO and IBF champion defends his titles on Saturday against former cruiserweight champion Usyk.

A cordial press conference today gave way to an intense face-off before a handshake between the pair.

Joshua, 31, said: "I'm not an easy fight for anyone, I like fighting."

He added: "If you tell me I was fighting King Kong I would give it a go. This is my job.

"I wasn't on the amateur scene long enough to know much about Oleksandr, but when I turned professional I did a lot of research and I love the Ukrainian style and the Ukrainian people.

Fury, 33, was forced to shelve plans to fight Joshua after being ordered by an arbitrator to face Deontay Wilder, leaving fans gutted to see the undisputed showdown fall through.

Joshua defends his WBA (Super), IBF and WBO belts against Oleksandr Usyk next and AJ's promoter says he would be shocked if the Fury fight did not happen.

"I don't want to speak badly about Fury's team, but I don't trust them. Really, we've got to look after ourselves and our own business, which is Oleksandr Usyk. The only thing that matters right now is that fight.

Joshua, 31, will risk his IBF, WBA and WBO belts against the Ukrainian, who is his mandatory challenger.

Usyk, 34, has not fought for a title as a heavyweight but held all four belts a division lower at cruiserweight.

Joshua was ordered to defend his WBO title after the collapse of his bout with fellow Briton Tyson Fury.

"We are two Olympic gold medallists who have fought our way to the top and never avoided challenges," Joshua said.

The all-British fight had looked set to take place in Saudi Arabia in August.

But it fell through when Deontay Wilder's team won an arbitration hearing stating the American had a right to a third fight with Fury.

"It might not be December or even next year," said Bunce.

The much anticipated fight between Fury and Joshua would have seen the pair contest all four world titles for the first time in the sport's history.

Fury is the WBC champion while Joshua has the WBO, WBA and IBF belts.

Britons Fury, 32, and Joshua, 31, had agreed to a heavyweight title bout in Saudi Arabia on 14 August.

But earlier this week a US judge ruled Fury must fight American Deontay Wilder for a third time by 15 September.

Hearn, Joshua's promoter, said the "game changed" with the ruling.

"We have to have a plan B in place. The one that springs to mind is the WBO mandatory - Oleksandr Usyk."

Less than a week ago Hearn told BBC he did not have any back-up plan in place because he was confident Joshua-Fury would be finalised.

Joshua, 31, holds the IBF, WBO, WBA and IBO titles while Fury, 32, is the WBC belt holder.

"August the seventh, August the 14th. I think it's a very bad secret that the fight is happening in Saudi Arabia," Eddie Hearn, head of Matchroom Sport and Joshua's promoter said.

Joshua won back his belts from Andy Ruiz Jr in Diriyah, on the outskirts of the Saudi capital Riyadh, in December 2019. He had lost the belts to the Mexican-American in an earlier shock defeat.

Hearn said Fury's lawyers were going through the fine details but an announcement could come this week.

The pair could also share about £95 million (NZ$183.6 million) in pay-per-view fees in a potential split with four major broadcasters as part of the biggest deal in British boxing history.

Saudi Arabia's main challengers are Shanghai and Singapore as promoters race to find a site after two-fight contracts to unify the world heavyweight titles were signed.

Logistical headaches of hiring and selling tickets for a 90,000 venue during the pandemic has all but ended hopes of the first fight taking place in London or Las Vegas.

Joshua beat Bulgarian Kubrat Pulev in December to retain his IBF, WBO and WBA titles and set up the prospect of a mouth-watering clash with fellow Briton Fury, the WBC belt holder.

Fury, 32, has not fought for over a year since his knockout win against American Deontay Wilder, but said last month he would fight twice this year.

ESPN reported that both fights are set to take place in 2021 with the first in June or July followed by the rematch in November or December.