1) Both achieved their most memorable successes at the age of 32 and only one year apart. In 1974 Ali regained the heavyweight crown in Zaire after coming back from an enforced 4 year lay off and beating George Foreman who, at the time, was considered invincible after destroying both Joe Frazier and Ken Norton, opponents whom Ali had struggled against. A year earlier, Bruce Lee's first major Hollywood production, Enter the Dragon was released worldwide and went on to become the most internationally successful martial arts film of all time - unfortunately Lee died a month prior to its release.
2) Ali was a huge fan of Lee and the feeling was most certainly mutual. Lee idolised Ali believing him to be the best of all time (a view shared by Ali himself), in fact Lee used to repeatedly watch recordings of Ali's fights, studying his movement around the ring to improve his own suspect lateral movement.
3) In fact much of the fight action in the scene from Way of the Dragon between Bruce and Chuck Norris was choreographed to mirror the 2nd and 3rd rounds of Ali's fight with Cleveland Williams.
4) Both men were fiercly protective of their race. Ali became a devout follower of the Nation of Islam, campaigned for civil rights, refused to be inducted into the US military forces on the grounds that he didn't want to fight other coloured folks in vietnam and repeatedly spoke out on issues of black pride, encouraging fellow negoes to find out more about their history and culture and to marry their own. Lee used his movies as vehicles to show the chinaman as the victorious underdog - In The Big Boss Lee fights the good fight aginst the tyrannical Thai bosses who are bullying his fellow chinese workers. Fist of Fury shows Lee fighting on behalf of his fellow chinese martial artists against the evil Japanese martial arts school who killed his teacher and destroyed his own school. Way of the Dragon pits Lee against an Italian mob who are demanding protection money from his family's restaurant, Lee also has to defeat an American Karate champion in the process. In Enter the Dragon Lee's main fight scene has him killing a fierce American bodyguard who had attempted to rape his sister.
5) Ali was famed for his fast footwork and often used to tell of how he intended to dance through a fight. Lee himself was no slouch in this department and in the late '50's was crowned the cha-cha champion of Hong Kong.
6) Both men were fanatical about fitness, Lee's philosophy being, 'one may know all the fighting techniques in the world but if one is not fit then one does not stand a chance in a real fight'. Ali, being involved in over 50 real fights was obviously an advocate of this opinion.
7) Bruce Lee is the most written about martial artist in history. Almost 30 years after his death, his life is still chronicled in martial arts magazines across the world. Several years ago, Ali bacame the most written about human being in history, overtaking Jesus Christ.
Both had immense impact on their respective sports. The interest in boxing during the mid-70's was due largely to the fact that Ali was widely regarded as the most recognisable face on the planet. Lee's impact on the martial arts scene was arguably even greater. Prior to Lee the number of martial arts schools across the globe could be measured in the low hundreds - a decade later the number could be measured in the tens of thousands.