It is the richest prize fight ever staged in Northern Ireland. The contestants are both among the best fighters ever to emerge from a province noted for its boxers, once the best of friends, now very much in opposite corners.
The stakes are high for both Barry McGuigan and Carl Frampton. Carl is suing Barry, his one-time manager, for £6m, but is facing a counter-claim for £4m.
These are eye-watering sums, the biggest purse either man - both world champions - have ever stood to win.
But this time they are not in the ring, but rather in the marbled halls and panelled courtroom of the Northern Ireland Royal Courts of Justice - better known as the High Court in Belfast.
It is certainly a less raucous arena than the men were used to in their fighting careers, but their legal representatives were determined to land a knockout blow if possible.
Carl (33) is claiming against Cyclone Promotions UK Ltd - of which Barry was a director - for allegedly withholding purse fees, broadcasting rights, ticket sales and merchandising.
He also claims that he never received a 30% profit share promised when he became director of another, Northern Ireland-based, Cyclone company. Barry's counter-claim is for alleged breach of contract when Carl left the company in 2017.
Both men deny the allegations against them.
This week, Carl spent a total of 22 hours in the witness box facing a wide range of probing questions.
What emerged was how a friendship turned toxic and has soured irrevocably.
It had all begun so well, with Carl becoming a two-weight world champion.
Counsel for Barry put it to Carl that his manager had sacrificed big paydays for the good of the fighter by allowing other promoters to stage his title bouts in the United States.
Counsel also argued that Carl was "no little lost boy", but had a major say in his purses.
He added: "I'm suggesting you had deep and many discussions about how much you were going to get and you fully understood the way the fight game worked as well."
Carl blocked this jab - "I disagree" - and came back with some of his own.
He argued that Cyclone Promotions could not successfully promote fights in the US and that is why other promoters had been used. He also gave a hint of how the case would develop over the week.
He said his wife had a run-in with Shane McGuigan, Barry's son. "Shane was very disrespectful to my wife and I should have had her side. I think I was trying to keep both parties happy."
The following day, Barry's counsel tried to land some heavier blows. He claimed that Carl's current management company, MTK Global, had alleged links with a suspected crime boss, Daniel Kinahan, and could be seen as a front for a criminal organisation.
Carl again put up his defences: "I've heard the stories. I don't suspect anything." He added: "I don't make judgments. Do you believe everything you read in the papers?"
The court was also told that Carl had saved himself thousands of dollars by under-declaring purses for contests in America.
It was put to Carl that this amounted to false accounting, which would be classified as a criminal offence in the UK.
The court heard that, in his first world title bout against Leo Santa Cruz, Carl’s purse was $1.5m, but that only $500,000 was declared.
Carl tried to deflect the blow, saying it was a joint decision based on advice from Barry. But counsel hit back: “You were the one who wanted it brought down as much as possible, because you were the beneficiary of it. That actually saved you $300,000... you knew that signing a document saying your purse was $500,000 was a lie.”
Carl countered: “I knew that, but my team also knew that.”
The court was told that, before one fight, Carl had emailed his management team asking “could one of the lads forge my signature”, rather than post and sign the documents himself.
He told the judge: “Again, showing how trustworthy I was of the McGuigans and I was happy for them to do that.”
Later, he said that, if he had known Barry had been disqualified as a company director for a period in the 1990s, he would never have signed with him.
When he was asked if he knew his current promoter had been disqualified at around the same time, he replied “No.”
But he threw his own heavy body punch, which must have left Barry wincing: “Frank Warren has continued to put on huge boxing events for decades. He has a proven track record. If someone who (had been) disqualified as a director from a company, with no experience in managing fighters before, said, ‘I want to manage your career’, I would have said no.”
Carl’s accountant, Sean McCrory, said the boxer did not gain “a single cent” in tax savings from title bouts in the US. He told the court that his client still had to pay higher-rate income tax in the UK.
According to Carl, the final straw in his deteriorating relationship with the McGuigans came when the taxman called at his home in the summer of 2017 with a bill for nearly £400,000.
Mr McCrory said he had studied the Northern Ireland Cyclone company’s accounts, which showed accumulative losses by June 2015 of £300,000.
Two years later, after Carl was involved in two world title fights, he expected the financial situation to have improved. “They were two massive fights... those are the fights you make your money out of,” the accountant added. But he was shocked to find that the loss had increased to £500,000.
However, the most explosive evidence came on the final day (for now) of the hearing — the case has been adjourned until next month.
The manager of a gym where Carl completed his preparations for fights staged in Belfast described the atmosphere at Monkstown Boxing Club as “toxic”.
Paul Johnston said that, on previous training occasions, the boxer and his management team were a “tight unit”, but in July 2017, things had changed completely.
“There was a tangible, what I would say breakdown in the relationship. It seemed to be quite toxic.” Barry, he said was not there as often as before, while Shane, Carl’s trainer, showed little interest in the fighter.
“The camp wasn’t happy. There was definitely an air of grievance, or unhappiness, with Carl. He wasn’t a happy fighter,” Mr Johnston added.
But it was further comments that came like a punch out of the blue. Mr Johnston said Shane began talking quite negatively about Carl.
“He said that he was finished, he said that, at best, he had one more fight in him and that he didn’t really want Carl to retire, spend his money and come back, that he wasn’t going to train a bum essentially.”
Barry’s counsel tried to counter, arguing that Carl had already decided to leave the organisation and that would definitely have had an impact on his attitude.
He contended that Barry had been at the gym and had spoken to Carl on friendly terms while Carl was the one being distant.
But Mr Johnston had a different take on the situation: “I would suggest Carl shadow-boxing in a ring, sitting on a bike making weight, he was doing what he was meant to be doing as a professional fighter. I think other people, and how they treated him, was more different than what Carl was being.”
Counsel came back again: “He (Shane) accepts that he wasn’t entirely happy with the way he (Carl) was training. He thought his mind was elsewhere and he said something to you like, ‘He looks sloppy, his body has been there, but his head isn’t there’... in other words, his head wasn’t in the game.”
Mr Johnston stood his ground: “No, he said that he had one or two fights left in him and that he wasn’t going to train somebody who was a has-been essentially.”
The case resumes next month.