In poundage, Fury has shed the equivalent of a peak-condition, light-welterweight Hatton since returning to training a year ago. And like Hatton, Fury has had to deal with the torment which sometimes besets even those who appear to have it all.

When Fury departed the scene in October 2016 with his world title belts either removed or relinquished, and a statement saying he needed to focus on his medical treatment, he tweeted a link to a song performed by the American country artist T Graham Brown entitled "Wine Into Water", which includes the lines: "Tonight I'm as low as any man can go, I'm down and I can't fall much farther."

According to his father John, boxing has saved Fury's life and the showdown here in Los Angeles is reward for a remarkable transformation.

Now the best part of 10 stones lighter, Fury is favoured by many respected voices to create an upset on Saturday. It is testament to his commitment (and pedigree) that there is even an argument about the outcome.

In August, when the possibility of a title shot against Deontay Wilder took root, an email I received from one of the UK's leading bookmakers showed Fury as the odds-on favourite. Last month, a similar missive placed Wilder as the market leader.

In a poll of pundits in the November issue of Boxing Monthly, Wilder came out on top but only by 18 votes to 12. It is that kind of fight, one to send wise heads spinning.

The central theme of the debate is ring rust. How significant is a lengthy absence in an era when elite, pay-per-view fighters tend to box only a couple of times a year anyway?

Fury has fought twice - albeit in lesser company - since Wilder's last appearance, when the American beat Cuba's Luis Ortiz in March.

Wilder's boxing ability undervalued

In the build-up to his win against Wladimir Klitschko three years ago this week, Fury had only three contests in two and a half years. The issue this time for Fury is more about what he did to his body while he was away and whether the opposition he has faced since can possibly have prepared him for Wilder.

The failed comebacks of Hatton and David Haye in recent years have provided us with evidence of the difference between general conditioning and boxing fitness. How much of the guile and the ability to read an opponent has Fury rediscovered?

Wilder's boxing ability is undervalued. To win a bronze medal at the Olympic Games after only three years in the sport is a feat, even if his performances in Beijing in 2008 were scrappy.

Wilder succumbed in the semi-finals to the Italian Clemente Russo, who had beaten Tony Bellew's recent conqueror Oleksandr Usyk to reach the last four.

The gold medal in China went to Russia's Rakhim Chakhkiev, who was outpointed by Wilder in a USA v Russia international earlier in 2008. Such form is more than a mere slugger could have compiled and ought to act as insurance against complacency and the prevailing notion that Wilder can punch but can't box.

Six of Wilder's eight world title fights have gone at least into the eighth round and the win against Ortiz, in the 10th, underlines how he carries his power through the fight.

Aside from Ortiz, Wilder's opposition might belong in the Hall of Tame but he has a knack of getting the job done and, unlike some heavy punchers, has shown strong survival instincts when hurt, as he was against Ortiz and Eric Molina.

Fury, also, has recovered from adversity, climbing off the canvas in 2011 to beat Neven Pajkic, a Bosnian based in Canada, and the American Steve Cunningham two years later.

On both occasions, Fury was felled by an overhand right - a shot Wilder throws particularly well. But when it came to Klitschko, Fury carried conviction and concentration into the ring and proved much more difficult to hit cleanly.

In an interview for BBC Radio 5 live a couple of months later, Fury told me how he could become "forever frozen in November 2015", that his emphatic success against the long-reigning Klitschko might never be bettered as an achievement.

Now there is desire and ambition anew, and a win over Wilder - so soon after the comeback - would rank as another of the finest by a British boxer.

The fight is important for boxing too, the most meaningful heavyweight title contest in the US since Lennox Lewis dredged up a victory over Vitali Klitschko in the same Staples Center ring in 2003.

Promotional trailers are playing out on huge screens outside the 21,000-capacity venue and staff at the box office report that tickets are selling well. In a busy week of basketball and ice hockey at the Center, they are also expecting a sizeable "walk-up" on Saturday.

And beyond here, we are likely to be talking about a rematch or Anthony Joshua - or both - in 2019.

Great eras in boxing are defined by rivalries and the action here in Los Angeles might be the start of something special.