While BBC Sport understands final details are still being hammered out between Netflix, Saudi Arabian organisers Sela and both fighters' camps, Cardiff has firmly emerged as the frontrunner, with an official announcement expected this week.

It marks another dramatic twist in a saga that, only weeks ago, appeared destined for New York. A date at Madison Square Garden was so close to completion that plans were already being drawn up for a Manhattan news conference.

Instead, after Joshua and promoter Eddie Hearn refused to budge on their contractual right to stage the fight on British soil, the Welsh capital has taken centre stage.

BBC Sport takes a look at how Cardiff became the leading candidate to host what would arguably be the biggest event in British boxing in the 21st Century.

Wembley Stadium was long assumed to be the natural home for a meeting between the two defining British heavyweights of their generation. However, the path to making the fight was complicated by Joshua and Fury having signed separate agreements with Sela rather than a joint contract.

Joshua's deal explicitly stipulated that the bout must take place in the United Kingdom, whereas Fury's contained no such restriction.

That distinction proved critical when organisers and broadcast partner Netflix began lobbying to move the show to the United States.

Hearn acknowledged that virtually every other party involved preferred New York, with Matchroom even exploring what compensation would be required to waive the UK clause.

For a moment, that stand-off threatened to scupper the entire event. Fury publicly accused Joshua of stalling and briefly floated the prospect of a trilogy fight with Oleksandr Usyk.

But once Fury relented, organisers needed to find a British venue capable of satisfying the broadcast demands without leaving fans exposed to the British winter.

Cardiff, almost by process of elimination, became the answer.

The fight had initially been discussed for November but, with negotiations over the venue dragging on, it now looks set for December.

Staging an open-air stadium fight in the UK at that time carries immense risk.

While Wembley offers unmatched prestige, exposing tens of thousands of fans and a massive international broadcast operation to potentially freezing temperatures, wind and rain was deemed unacceptable.

Moving the event indoors to an arena like London's O2 would eliminate weather risks, but at the cost of sacrificing tens of thousands of ticket sales.

The Principality Stadium's retractable roof allows organisers to capture the immense scale, atmosphere and gate revenue of a stadium show while offering full protection from the elements.

The venue's official seated capacity is just under 74,000, but boxing configurations allow for even larger crowds.

Joshua has already proven he can sell out the venue, having defended his WBA and IBF titles there against Carlos Takam in front of nearly 80,000 fans in 2017 before adding the WBO belt against Joseph Parker five months later.

Perhaps the most difficult hurdle has been aligning the event with Netflix's preference to broadcast during prime-time hours in the United States.

A projected UK ring walk of about 01:00 GMT - 20:00 on the US east coast - created a logistical headache for London. Wembley operates under a strict 23:00 event curfew.

While Mayor of London Sadiq Khan offered his support and Wembley officials were open to discussions, securing the necessary approvals from Brent Council and local safety advisory groups for a 01:00 start presented an administrative hurdle.

Cardiff offers a far smoother path. The Welsh Rugby Union, which owns and operates the Principality Stadium, previously indicated it would be delighted to host the fight and confirmed a late-night finish would not be a dealbreaker.

While early-hours finishes still require extensive coordination around transport, policing and crowd management in the city centre, the venue already holds a clear precedent for late-night boxing. In 2007, Joe Calzaghe's super-middleweight unification victory over Mikkel Kessler did not start until 02:00 local time to satisfy American television network Showtime.

For all the delays and frustrations that have plagued this rivalry over the past decade, Fury against Joshua remains the pinnacle of domestic boxing. Downgrading to an indoor arena would diminish the magnitude of the occasion.

Crucially, taking the fight to America would have deprived domestic fans of a generational spectacle. British supporters have driven the commercial value of this rivalry for years, filling stadiums for both fighters' respective careers and following every collapsed negotiation.

Staging the bout on home soil serves as a long-overdue reward for that loyalty, even if both men are now former world heavyweight champions.

A stadium fight of this magnitude dominates the national conversation in a way a 04:00 New York or Las Vegas broadcast simply cannot, and local amateur boxing clubs could see a surge in interest when the country's biggest stars compete on home soil.

Wales also has history of staging a huge fight between two British heavyweights: In 1993, Lennox Lewis defended his WBC title against Frank Bruno at Cardiff Arms Park - the venue that the Principality Stadium replaced.

When the demands surrounding the event are broken down, Cardiff's emergence becomes easier to understand.