George Foreman fixes his interrogator with the kind of stare that once sent shudders through the very soul of his opponents, unblinking, menacing and with more than a hint of unbridled rage.

"It was bad enough to lose the fight, but to lose to Muhammad Ali, the biggest braggadocio on the planet, that was much more painful."

Forty years have passed since the Rumble in the Jungle, the night when Foreman went toe to toe with Muhammad Ali for the biggest prize in the sport, the world heavyweight boxing championship in Zaire

That's forty years for him to have finally come to terms with the defeat that saw his own career crash and burn, while Ali triumphed against all the odds in Kinshasha's stadium to become only the second man in history to reclaim the heavyweight crown.

The Rumble in the Jungle. The fight of the century. And the night when Ali sent Foreman, the baddest man on the planet, a fighter who had clubbed Joe Frazier into submission inside two rounds, spinning to the canvas in a never-to-be-forgotten eighth round.

YouTube now ensures we can watch the last few, mind-numbing seconds of the fight again and again at the touch of a computer button. On October 30, 1974, thousands packed into cinemas all over the world to watch the fight on closed-circuit television. In Britain, millions more watched on the BBC.

Even now the sound of Harry Carpenter declaring: "Oh my God he's won back the title at 32" echoes clearly down through the decades. It was spectacular and surreal and no less so now when seen through the prism of those grainy films and the award-winning documentary movie When We Were Kings.

But the compelling story of The Rumble in the Jungle extends far beyond that sweltering night in Kinshasa a few hours before dawn under an African moon. And to understand the narrative, you have to go back seven years earlier, to 1967, when Ali cited his conversion to Islam as his steadfast reason for refusing to be conscripted into the American military to fight in Vietnam.

"I ain't got no quarrel with them Vietcong," was his principled stance, one that eventually saw him stripped of his title and exiled from the ring for four years.

When he returned, he was no longer the dancing master from Louisville, Kentucky, and the belt he felt was rightfully his now fitted snugly round the waist of Joe Frazier. Having traded bitter public and private insults, the two men eventually met in the ring, Frazier sending Ali to the floor on his way to a 15-round points decision.

The defeat saw Ali once again banished to boxing's outer margins and so began a laborious,three-year 14-fight journey to earn himself another shot at the title.

In the pages in between, Frazier had lost his title to Foreman during two typically brutal rounds of boxing, which climaxed with one punch lifting Smokin' Joe clean off his feet.

Only one name now remained on Foreman's dance card. So the stage was set but months of negotiations turned into financial deadlock before one man stepped out of shadows to offer both men the then eye-watering sum of $5 million.

Don King, a smooth-talking hustler who had served time for manslaughter had found a niche as a boxing promoter operating largely in the sport's margins, fixing deals for journeymen. The Foreman-Ali fight offered King a way out of boxing's ghettto into the big time.

Both fighters signed the contracts and Ali became King's cash cow. Trouble was, King didn't have the £10 million and he set about hawking the fight to the highest bidder.

At this point another dubious character joined the cast of the Rumble in the Jungle. Mobutu Sese Seko, the despotic president of Zaire, offered to host the fight in the capital Kinshasa, in the arena named after the day he had seized power, the May 20 Stadium. Crucially he put up the purse.

The money undoubtedly came straight out of the purses of the Zairian population, but this hardly seemed to matter - Foreman and Ali had sealed their pact with the voodoo king.

And so it was that this African backwater, with its crippling poverty and rampant inflation, became the unlikely setting for what Ali quickly termed The Rumble in the Jungle.

The contrast between the two fighters could not have been greater; Ali was 32 and a long way from the young prince who a decade earlier had first won the heavyweight title by stopping Sonny Liston, while Foreman, at 25, was at the top of his game, hugely muscled and bristling with awesome power.

Foreman was monosyllabic and sullen, and cut an isolated figure, preferring, it seemed, the company of his German Shepherd guard dogs. Ali, in contrast, treated his arrival in Zaire like the spiritual homecoming of a black apostle as he whipped up the local crowds into something akin to religious fervour. "Ali bomaye," chanted the Kinshasa choir - Ali kill him.

But beneath the bluster, Ali's personal life was in meltdown. His huge entourage included an 18-year-old actress and model called Veronica Porsche, while his second wife Belinda stayed in America. But she soon hightailed it to Africa to confront Ali when she heard him refer to Veronica as his wife.

The fight then had to be postponed after Foreman suffered a cut in training and threatened to scrap the whole thing. Legend has it that Mobutu ordered a curfew on both boxers to ensure they stayed in his country until fight night arrived.

Most people were convinced Ali would be dispatched in the same, brutal manner as Frazier and Ken Norton. Some, including literary heavyweights Norman Mailer and Hunter S Thomson, both assigned to cover the fight, genuinely feared his life was in mortal danger. Adding to the surreality surrounding the bout, Frank Sinatra, unable to get a ticket, bagged a gig to cover it as a photographer for Life magazine

What happened next, of course, is the stuff of boxing folklore. From the opening bell, Ali tore at ­Foreman, catching him with several big right hands before retreating into clinches mid-round then coming on strong at the end.

By the third round, Ali had employed the "rope-a-dope", a seemingly suicidal tactic by which he lay back on the ropes and allowed Foreman to unleash crippling shots to the body. Few of them landed with any accuracy and it was Ali who held the upper hand.

By the seventh round, Foreman was flat footed and puffed out, his punches little more than shoulder taps. Halfway through the eighth round, Archie Moore, the former heavyweight champion in Foreman's corner, tried to exhort Foreman into one last effort.

Disdainfully, Ali held Foreman in a headlock before glowering at Moore and telling him: "Quiet, old man, it's all over." A minute or so later it was, Ali felled Foreman with two right hand blows that signalled that he had, incredibly, fulfilled his mission to regain his title.

An hour later, Kinshasha suffered an almost Biblical rainstorm, but the boxing gods that night smiled on Muhammad Ali.

Looking back, Ali should have chucked it and bowed out when he truly was king, but vanity and ego are a boxer's biggest adversaries and their siren song drove the man they call the Greatest on to the rocks of his own downfall.

He fought 14 more times, including the jaw-shuddering third fight against Frazier, the Thriller in Manilla. He lost and regained the title fighting Leon Spinks before bowing out for good in 1981 at 39 after losing a points decision to Trevor Berbick, his once glowing talent all but extinguished and already suffering the early onset of Parkinson's Disease.

Foreman retired in 1977 and found God before returning to the ring in 1994 and becoming the oldest heavyweight champion in history after beating Michael Moorer.

But it will for his part in the Rumble in the Jungle that Foreman will always be remembered. Today the dichotomy between Ali and Foreman remains but for different reasons. Ali is now a husk of a man crippled by Parkinson's, his once-agile mind barely registering. Foreman, on the other hand, is a smiling, much-loved hero from a golden age of boxing, the scars from the Rumble in the Jungle long since healed. And what does he now thing of Muhammad Ali, the biggest braggadocio on the planet?

He says: "As the years have gone by, I realise he is one of the greatest men I ever have met. He's too big to merely categorise as the greatest boxer. That makes him small. Each year that goes by, his life means more to me."