Floyd Mayweather vs Manny Pacquiao will be the biggest fight of all time financially and the most significant this century. Evaluating the greatest ever fights is a complex variable of several factors including not only the quality and excitement of the action but the political, social and cultural undertones, the scale of expectation and outside influences. Where Money Man vs PacMan comes to rank among the most important fights in ring history will depend upon what happens that coming night in the MGM Grand Garden Arena. In this, the third in a series of 12 fights that shaped boxing history, I look back on one of the most anticipated events of the 20th century which divided a nation. THE SECOND FIGHT OF THE CENTURY . Joe Frazier v Muhammad Ali . Madison Square Garden, New York . March 8, 1971 . The Greatest had been stripped of the world heavyweight title he had won so sensationally against Sonny Liston but it was the reason for that decision which added cultural significance to what was to be a magnificent fight. Sweat sprays off Muhammad Ali (right) as Joe Frazier collects his jaw with a strong left in 1971 . Ali and Frazier at Madison Square Garden, New York, on March 8, 1971, was the second 'Fight of the Century' Ali's evasive abilities and speed, such as this swerve from a Frazier hook, kept him in the fight . Smokin’ Joe was the undefeated two-belt champion but it was this proud black man’s bizarre adoption by America’s conservative right which stoked the fires of society still further. Muhammad Ali had been banned from boxing for three-and-a-half years for refusing induction into the US military to fight in Vietnam – but as a consequence become the darling of the young, the black and the Civil Rights movement. Joe Frazier found himself unwittingly the standard bearer for the white establishment. Ali fanned the flames by labelling the simpler man who would become his arch-rival an ‘Uncle Tom,’ the most wounding insult for an African American . There was a foretaste of the current scramble for Mayweather-Pacquaio tickets. Woody Allen was one of the very few celebrities give a complimentary seat and other famous names had to work their way into the 20,000 crowd at the Garden. Frank Sinatra persuaded Life magazine to give him a camera and send him as their ringside photographer. Fast-talking Ali offensively labelled Frazier an 'Uncle Tom' due to the support he got from white conservatives . Referee Tony Perez, widely believed to have acted leniently in Ali's favour, orders the pair to their corners . JACK JOHNSON v JAMES JEFFRIES . July 4, 1910, Reno, Nevada . JOE LOUIS v MAX SCHMELING . June 22, 1938, Yankee Stadium, New York . Author Norman Mailer reported on the fight. Actor Burt Lancaster picked up a TV microphone for his only stint as a colour commentator. Artist Leroy Neiman sat at his easel painting Ali and Frazier as they fought. This was one fight in which the action fully lived up to the hype and its place in history. Ali came out fast to dominate the first three rounds. Frazier, encouraged by catching Ali with the last punch of the third, launched an attack to the body in the fourth which brought him into the ascendancy. Ali’s speed of hand, dancing feet and combination punching kept him in a fight in which he was taking increasing punishment – along with a little help from referee Arthur Mercante who declined to call a knock down when Frazier sent him crashing in the eighth. Ali is laid out on the canvas as Frazier is send to the corner before a long 10-count in the 15th round . Somehow, heroically, survived the especially torrid 11th and 14th rounds. Still some good judges had it close going into the 15th and last round. There all argument was ended. Frazier caught him with the most wicked of all those trademark left hooks and this time there was no denying a count which appeared to edge a fraction longer than the stipulated ten seconds. Ali rose to his feet. Unsteadily. His jaw grotesquely swollen. Again his courage carried him to the bell. The decision was unanimously in favour of Frazier, although both men went to hospital. Frazier got the unanimous decision from the judges but both men went to hospital after the epic bout . Very late that night word spread through New York’s animated bars that one of them had died. Frazier checked out early, quietly. Ali pronounced the rumours of his passing to be premature. Their trilogy was born. They were to fight twice more and on one of those occasions each would come close to death again.
Floyd Mayweather Jr and Manny Pacquiao's fight will be the richest ever .
Sportsmail's Jeff Powell is counting down the ring's most significant fights .
Joe Frazier v Muhammad Ali in New York in 1971 is the third in the series .
Smokin' Joe was two-belt champion bizarrely backed by conservatives .
Ali was darling of young blacks after refusal to fight in Vietnam .