Two years ago this very week I was holed up in a hotel on the city limits of Philadelphia. An election was taking place too, congressional rather then presidential, and the lobby was full of upbeat campaigners wearing buttons and waving novelty sponge hands. Back then I was skulking around the lobby waiting to meet another extraordinary black American - a boxer who took part in a contest that is unlikely to be bettered. His name is Joe Frazier and he was once the heavyweight champion of the world.
Not that most people would know, however. Philadelphia is the birthplace of American independence, yet its biggest tourist draw is probably the Rocky Balboa statue at the foot of the art museum steps. What makes the statue so depressing is that not only is it a tribute to a fictional boxer, but that Sylvester Stallone burgled Jospeh William "Smokin' Joe" Frazier's life story for his Rocky movies. It was Frazier who worked in a Philly slaughterhouse, pounding the huge sides of beef in his down-time; it was Frazier who trained by running up those steps; and it was Frazier who went head-to-head with Muhammad Ali in the 1970s in a trilogy of fights now known as the pyramids of boxing.
These days everybody knows about Muhammad Ali but very few remember the other man in the ring. Once you know Frazier's story, though, you may never look at Ali "The Greatest" in the same light again. After all, this is the man who racially taunted Frazier at the pre-match press conference by calling him a "gorilla".
The film I ended up making wasn't just about boxing, it was about the racial politics of 70s America and personal betrayal which culminated in the Manila bout that Ali described as, "the nearest thing to death".
Too young to have remembered the actual fight in Manila in 1975 I had, over the years, read Frazier's occasional utterances. Things like, "When a man gets into your blood like that you can never let go. No matter. Yesterday is today for me. He never die in me." This was dark shit. Not exactly the sort of stuff you hear from David Beckham.
After several days of waiting, Frazier's manager finally picked me up and I was driven to a part of town where the political campaigners wouldn't be going. Joe Frazier is still at the gym where he trained for his very first fights - 2917 North Broad Street, Philadelphia. It sits bang in the middle of one of America's worst ghettos (known to the locals as "The Badlands") and looks like a scene from The Wire, a gunned-out area blighted by poverty and drugs, with streets of empty row houses.
Frazier lives in the gym, in a room out the back, just like Morgan Freeman's character, Scrap-Iron, in Million Dollar Baby. Our first meeting was surreal. He emerged from the back dressed like Jay Gatsby. Immaculate. His opening gambit was, "Why you want to make this film now? Why didn't you come earlier? I've been here since 1964. Why now?" His tongue may have been in his cheek but a note of bitterness and wounded pride was unmistakable. And who can blame him? While Ali recently sold his image rights for a cool $50m, Frazier remains in his gym, forced to live in the shadow of the man who betrayed him.
When Ali was stripped of his title after refusing to fight in Vietnam, Joe Frazier - who inherited his heavyweight crown - remained loyal, supporting him financially. But when Ali was given his boxing licence back he quickly turned on Frazier, and twisted their first fight into a race war calling Frazier an Uncle Tom - "the white man's nigger". That 1971 fight at Madison Square Garden in New York became a metaphor for an era: racial politics, Vietnam and showbiz glitz (Frank Sinatra was the ring photographer, Burt Lancaster a co-commentator). Against expectation, Frazier won in a 15-round epic. He had become the first man to beat Muhammad Ali. In turn, Ali won a hotly disputed second Garden fight, making it all to play for in the Philippines.
But what unfolded in the searing heat of Manila on October 1, 1975 (local time) went beyond boxing, beyond sport. It was the dramatic culmination of a blood feud. Extraordinarily, Frazier, since the day he stepped out of that ring, had never watched the fight. I guess it's no surprise. When Ali was once asked to watch the Thrilla In Manila fight again he flatly refused, saying, "I don't wanna see hell again."
I spent months trying to persuade Frazier to watch the fight. It was that sort of documentary, one in which the former heavyweight Larry Holmes exploded with rage several inches from my face and Imelda Marcos asked me to help her get back her gold bullion from a Swiss bank. Joe Frazier eventually agreed to watch the fight. It's quite extraordinary, he doesn't say much but his eyes say everything ...
• True Stories, Thriller In Manila, Tue, 10pm, More4; Sheffield Doc/Fest, tonight
