‘I’m just ready to fight,” Anthony Joshua said earlier this month as he looked ahead to his bout against Daniel Dubois at Wembley Stadium on Saturday night. Dubois sat opposite Joshua at a table in a television studio and, replicating the often manufactured drama which pre-fight shows are meant to generate, he looked coolly at his more famous opponent and said: “Let’s go.”

His promoter Frank Warren, sitting alongside Dubois, smiled and added a little caveat to dilute the sudden intensity: “But let’s wait until the 21st.” Dubois, for once, ignored Warren and continued: “If he wants to swing, let’s go now.”

“Shaddup,” Joshua snapped. “Relax.” Dubois looked relaxed enough but he was not willing to drop his provocative invitation. “If you want to go now,” he said, staring at Joshua, “let’s go.”

Joshua, who is usually criticised for being too sanitised and almost corporate in his public appearances, reacted with unusual force and profanity. “I’ll put this fucking chair across your face,” he warned Dubois. “Don’t disrespect me.”

“You can’t intimidate me,” Dubois replied. “Who do you think you are?”

Joshua, looking suddenly menacing in his white vest, stood up and walked towards his younger rival. Dubois, wearing a crisp white business shirt and black waistcoat, also rose to his feet with alacrity. A beefy security guard, meanwhile, jumped between the fighters as Warren and his promotional counterpart Eddie Hearn tried to calm the mood.

But, before he was led away, Joshua spoke seriously to Dubois: “Dan, I don’t take disrespect lightly. Don’t sit at the table telling me we can go now, trying to call me out.”

Such minor altercations often seem deeply contrived as television producers bring boxers together in an effort to generate spiky “content” which will boost their pay-per-view sales. But this is not how Joshua normally reacts and it suggested that he might feel under pressure as, yet again, he faces an opponent against whom it would seem disastrous to lose.

Joshua has lost three of his 31 fights in a heavily scrutinised professional career which began 11 years ago, in the autumn of 2013. He has been a two-time world champion, who has made more money than any other British boxer in history, but his painful defeats scarred him. The 34-year-old is now driven to end his career on a high and become an undisputed world champion and so wipe away the residue of disappointment which still lingers inside him.

Oleksandr Usyk is the real champion, having won all the belts of the four major sanctioning bodies when he beat Tyson Fury in an unforgettable fight in May. But, typically of boxing, he was stripped of his IBF title for refusing to pull out of his contracted rematch with Fury in December. The IBF had insisted that Usyk should fight their chosen mandatory challenger, who happens to be Dubois, but the admirable Ukrainian refused to buckle.

Usyk beat Dubois last August and he has already defeated Joshua twice. Yet the greedy chaos of boxing politics meant that Dubois was appointed as the IBF’s new ‘world’ champion and his first defence is against Joshua. It should still make for an intriguing matchup because Dubois is seven years younger and, despite two losses on his own record, he is hungry for the recognition that Joshua has lived with for years.

But Joshua is in a much more amiable mood now. He discusses his confrontation with Dubois and adds some surprising detail. “I’ll give you the gist behind it, right,” he says cheerfully. “I was in the pub the week before [the face-off with Dubois]. Obviously I’m not going around as much and there’s a new generation coming through. One little kid – well, I’m 35 [next month] and he’s probably 30-something – thought he could say something. I felt that disrespect [because] you can’t let anyone think they can speak to you in a certain way. At the pub, there are other people who are looking at this person talking to me like that. So don’t ever think you can disrespect me – because it won’t end well for you. So, we drew a line under that.

“Then, the week after, I’m doing a face-off and [Dubois] tried to get mouthy. So I’m still in the same mindset. What happens if Jarrell Miller or Deontay Wilder starts thinking they can talk to me like that?

“So, Dan, I’m gonna put a stop to you there and listen: ‘I will smash this fucking chair across your face, and I’ll ram the pole down your throat.’ You have to let someone know that you’re not fucking about, and hopefully that will ripple out to everyone else.”

Joshua smiles in his more usual way to show that there was nothing personal in his threat to Dubois. “I don’t want any problems but I’m in an industry where I’m fighting. I’m not playing golf, I’m not playing tennis. I’m in a sport with men with testosterone – gladiators that will take any opportunity to try to belittle you and test your toughness.

“It was calculated and stemmed from that night before. It wasn’t sporadic. I just realised you can’t let anyone get an upper hand on you. Whether it’s Dubois saying ‘Let’s go’ or the guy in the pub swearing about me, I’ll say: ‘What? Don’t ever think you can talk like that.’”

In his last two fights, which were decisive stoppage wins over Otto Wallin and Francis Ngannou, Joshua was much more aggressive and brutally clinical. Asked if that renewed edge in the ring, which has been sharpened by his new trainer Ben Davison, is still overlooked, Joshua leans forward.

“I’m a nice person,” he suggests, “but honestly, I’ll switch as well. So, you pick what side of the fence you want to sit on. Most people are all right with me, but I will definitely go to extremes that I don’t think they’re ready for. It’s up to them which way they wanna do it. With Dan there’s no problem. I like Dan, there’s nothing wrong with him, he’s a good guy. We’ll shake hands after. But it was the fact that someone thought they were OK to say: ‘We can fight now.’ Am I gonna say: ‘Nah, let’s not go now, I’m not ready’? Are you crazy? I’m gonna give it back to you.”

Joshua gives the typical shrug of a veteran fighter. “It’s the industry I’m in. You have to be this way.”

That hardened experience will help Joshua amid the seething atmosphere produced by an all-British clash in front of a crowd of 96,000. There are some doubts that Dubois, who hits hard and presents a real danger to Joshua, will cope as well with the raucous occasion. But Joshua, who understands the elation and despair of boxing better than most, is surprisingly supportive of Dubois.

“I think he’s gonna be fine, honestly. You have no other choice but to rise to the occasion, unfortunately. You’ve come this far. He’s walked out at Tottenham [Hotspur Stadium], he’s walked out in Poland [where he fought Usyk in another stadium bout]. He’ll walk out at Wembley.”

That show of respect for Dubois stands in stark contrast to their recent spat over a chair in a television studio. Joshua pauses and then, with quiet certainty, adds one last hard-bitten truth about boxing and all that awaits him and Dubois: “Once that first bell goes you’re in the fight, and it doesn’t matter any more about anything.”