The 28-year-old IBF and WBA champion faces Carlos Takam at Cardiff’s Principality Stadium on Saturday.

A win will fuel talk of unifying the titles with the WBC crown of Deontay Wilder and Joseph Parker’s WBO version. Carlos Takam has replaced Kubrat Pulev as the challenger to world heavyweight champion Anthony Joshua on 28 October after a shoulder injury forced the Bulgarian to withdraw.

The Frenchman Takam, also 36, will replace him with less than two weeks’ notice, meaning Pulev will face a long wait to fight Joshua after also losing his status as mandatory challenger with the IBF.

“It’s difficult for AJ. Having prepared meticulously for the style and height of Pulev, he now faces a completely different style and challenge in Takam,” said Joshua’s promoter, Eddie Hearn. “This hasn’t happened in his career before but he is ready for all comers.

“History is a great thing to chase,” Briton Joshua told BBC Sport. “It’s very possible and a great challenge.” Asked if timing fights to satisfy all four sanctioning bodies made the task difficult, Joshua replied: “We will find a way to make it happen.

“It’s like a diamond in the dirt, the treasure, trying to get that pot of gold at the end of the rainbow.

“If we can make it happen, I will be up for it – but if not, it’s not the end of the world and leaves a record to break for someone else.”

Mike Tyson held three heavyweight titles in 1987, before the formation of the WBO.

Since that body was created, no man has held four titles, with Evander Holyfield, Riddick Bowe, James ‘Buster’ Douglas, Lennox Lewis, Wladimir Klitschko and Tyson Fury all laying claim to three belts at once.

At Thursday’s final news conference before his meeting with France’s Takam, Joshua stressed he wants to put April’s Wembley victory over Klitschko behind him.

“The mindset of a fighter has to be leave that last fight where it was and move on to the next opportunity,” said Joshua.

“If I am living off past wins I may as well give up. I can’t lose this fight and say ‘I won a good one last time’. No-one cares.”

Joshua’s coach Rob McCracken said the change of fighter was “not ideal”, adding that Takam was a “live” and “dangerous opponent”.

Joshua also described the Cameroon-born fighter as a “different animal” to Klitschko, but said he feels comfortable with the late change. “Whether I was fighting Pulev, King Kong or Takam, he’s trained me to be me – thinking about balance, footwork and hand positioning.”

Takam has never challenged for a recognised world title and said Saturday’s event – under a closed roof at Wales’ national stadium – will change his life.

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Joshua’s promoter Eddie Hearn said: “British boxing has never seen anything like Joshua before in terms of draw and crowd sizes. He is a complete phenomenon.

“It has happened vey quickly for Joshua, 19 fights. I think fans understand he is vulnerable. He is not the finished article and he loves to fight.