It was once so clear and powerful. The heavyweight championship of the world used to be the most significant prize in sport and the winner was often as revered or feared as almost any man on the planet. As Tyson Fury and Oleksandr Usyk prepare to face each other in Saudi Arabia on Saturday night, with both men determined to become the first undisputed world heavyweight champion this century, it feels timely to remember those simple yet majestic years in the ring.

For decades in the 20th century only eight men could claim to be a world champion at any given time and such clarity made boxing a compelling business. Variations came and went but, at boxing’s peak, there were just eight weight divisions, with the heavyweight champion occupying an exalted place in sport and society.

Heavyweight boxing also broke down previously unshakeable racial barriers as African American fighters, inspired by the audacious Jack Johnson and bolstered by the stoical Joe Louis, swept aside inferior challengers peddled year after year as “The Great White Hope”. Johnson was hated by many white Americans because he mocked racism and celebrated his “unforgivable blackness”. He enjoyed the wealth and fame bestowed on the world heavyweight champion and openly paraded his white girlfriends and dapper suits.

When he was challenged by Jim Jeffries, who vowed to prove the supremacy of the white race by winning the title in 1910, the champion’s skill and power resulted in a crushing victory for Johnson and black America.

In the 1930s boxing still dominated the sporting mainstream in America, filling newspaper pages and echoing on radio broadcasts with a power and urgency difficult to imagine today. It also carried a political resonance. Louis had been shocked in 1936, when he was 21 and lost for the first time to Germany’s Max Schmeling. Adolf Hitler was jubilant, claiming Aryan supremacy, even though Schmeling did not support the Nazis.

Louis, who was instructed by his managers to do the opposite of Johnson, said little and hid his emotions behind an impassive mask. It helped curb a racist backlash when Louis became world champion a year later and then, in June 1938, defended his title in a rematch with Schmeling. Hitler was convinced Schmeling would prevail but Louis, punching with fire and fury, won by a first-round knockout.

The Nazis terminated the state radio broadcast to Germany as soon as Schmeling went down for the first time. When the fight was waved over, after two minutes and four seconds, thousands of black Americans rushed from their radio stations at home in New York. They took to the streets and ran, screaming with joy, towards giant banners unfurling from tenement blocks with the message: Joe Louis Wins, Hitler Weeps.

Muhammad Ali did even more for black America in the 1960s and 70s when, despite being banned from boxing for three years because he refused to fight in the Vietnam war, he resembled the King of the World. Other great heavyweights – Sonny Liston, Joe Frazier, George Foreman, Ken Norton and Larry Holmes – spanned the wondrous era of Ali. They ensured that boxing still transfixed the sporting world.

When Ali returned from the wilderness, having been stripped of his world title during his fallout with the US government, he and Frazier shared an unforgettable trilogy. The first bout, at Madison Square Garden in March 1971, was called The Fight of the Century. Demand to see an epic showdown was so intense that Frank Sinatra had to take photographs for Life magazine to get into the Garden.

The heavyweight scene fragmented in the late 1970s and early 1980s. But the ferocious young Mike Tyson, who understood and treasured boxing history, became the undisputed world champion in 1987. For the next three years Tyson was the “Baddest Man on the Planet” as, amid his own confusion and trouble, he left a trail of devastation in and outside the ring. But with the inevitable demise of Tyson, confirmed by his shock defeat to Buster Douglas in Tokyo in 1990, the heavyweight title lost much of its lustre.

Two outstanding world champions, Evander Holyfield and Lennox Lewis, fought twice in 1999. After Lewis was denied his rightful victory by an outrageous draw in the first fight, he won the rematch in November that year. It was the last time boxing could proclaim an undisputed world heavyweight champion.

Now, more than 23 years later, Fury and Usyk will try to join the pantheon. Their bout has been postponed twice since last October in chaotic scenes which mirror the state of contemporary boxing. It’s very different to the glory days.

Today there are 17 weight classes and the four main sanctioning bodies and warring promoters often prevent the best fighters from meeting in the ring. The IBF, WBA, WBC and WBO anoint their own “world champion” in each division and draw up ratings which ignore challengers associated with rival organisations. It’s difficult for unification contests to happen because each respective champion has to defend his “world” title against mandatory challengers favoured by his sanctioning body – which take a chunky cut from each championship contest.

Promoters have the power to ignore the alphabet boys, because most fans have little idea of which belt belongs to whom, but until recently they usually refused to work with their rivals. So we have endured boxing’s equivalent of Real Madrid never facing Manchester City, Bayern Munich, Paris Saint-Germain or Inter in the Champions League because rival leagues in Spain, England, Germany, France and Italy refuse to allow their best clubs to play each other. In an absurd scenario for football each club would claim to have won their version of the Champions League against mediocre opposition.

The belated fact that Fury, the WBC champion, will now face Uysk, who holds the IBF, WBA and WBO titles, is a sweet hit of purity to the poor old boxing fan who has been ignored for so long. Yet it has needed Saudi Arabian money to make this unification contest finally happen.

Boxing has always been a murky business. Even Ali, the greatest of them all who did more than any other boxer in calling out prejudice and injustice, fought in countries as repressive and corrupt as Zaire [now the Democratic Republic of Congo] and the Philippines when it was ruled by Ferdinand Marcos.

In 1974’s Rumble in the Jungle, Ali shocked the world all over again when he defeated Foreman but the bout was used by Zaire’s president, Mobuto Sese Seko, to drum up publicity for his totalitarian regime. Ali then beat Frazier a year later in the Thrilla in Manilla but one of the most remarkable if savage fights in heavyweight history was also used by a dictator as a publicity stunt. The corruption, brutality and greed of Marcos in the Philippines was relentless.

We are back in controversial territory but, just days from this rare unification contest, there is a real fascination in a clash between two contrasting champions. They will never match the magnitude of Johnson and Louis, Ali and Frazier, but Fury and Usyk are gifted fighters.

Fury’s outrageous personality transcends the limited confines of boxing today, while Usyk rises up as a symbol of Ukrainian resistance and hope during a ravaging war with Russia. The winner will restore some clarity and order, if only briefly, to the madhouse of boxing.

Heavyweight title fights that shook the world

Jack Johnson v Jim Jeffries, Reno, Nevada (10 July 1910) Jeffries came out of retirement to challenge the bold and brilliant black world champion, Jack Johnson. The deeply racist challenger insisted he would prove that “a white man is better than a Negro”. But he was no match for Johnson who forced Jeffries to quit in the 15th round. Race riots broke out but Johnson remained imperious.

Joe Louis v Max Schmeling, Yankee Stadium, New York (22 June 1938) Two years and three days after Louis had suffered a shattering defeat to Schmeling he returned to the same venue as the new world champion. His rematch with Schmeling was fraught with global significance. With the second world war looming Hitler expected the German to prevail again – even though Schmeling abhorred nazism. But it took Louis just two minutes to shatter the myth of Aryan supremacy.

Joe Frazier v Muhammad Ali, Madison Square Garden, New York (8 March 1971) In the ‘Fight of the Century’, Ali challenged his increasingly bitter rival, Frazier, who was the world heavyweight champion. Ali had been stripped of that title when his refusal to face conscription to the US army during the Vietnam war resulted in a three-year suspension from boxing. Frazier won a gruelling 15-round battle clearly on points.

Muhammad Ali v George Foreman, Kinshasa, Zaire (30 October 1974) Ali regained the world title when, with audacious nerve, he suckered the then frightening Foreman with his canny rope-a-dope strategy. Foreman tore into Ali, who absorbed or deflected the heavy bombardment while staying on the ropes. It was a startling tactic which befuddled and exhausted Foreman before, in the eighth round, Ali sealed an astonishing knockout.

Buster Douglas v Mike Tyson, Tokyo Dome, Japan (11 October 1990) In the biggest shock in world heavyweight title history, Douglas, grieving the recent death of his mother, withstood the expected early assault from the ferocious if deeply troubled Tyson to produce an astonishing victory. Douglas, a rank outsider who had lost four previous bouts, produced the performance of his life as he stopped the seemingly invincible Baddest Man on The Planet in the 10th round.