Classic photos of Muhammad Ali

(AP Photo)

Muhammad Ali looks on during a bout between Terry Norris and Carl Daniels. (Holly Stein/Getty Images)

Muhammad Ali lands a right to the head of Brian London during their World Heavyweight Title fight at Earls Court. Ali won by a knockout in the third round. (Getty Images)

Muhammad Ali touches a younger version of himself which is on the special edition Muhammad Ali Wheaties' box that marks the cereal's 75th anniversary 04 February. Wheaties, "The Breakfast of Champions," is honoring the man widely accepted as one of the greatest athletes of all time. (HENNY RAY ABRAMS/AFP/Getty Images)

American boxer Muhammad Ali looks out over London from the top of the Post Office Tower, 25th July 1966. Ali is in Britain to defend his World Heavyweight title against Brian London. (Keystone/Hulton Archive/Getty Images)

World heavyweight boxing champion Muhammad Ali during a press conference at the Savoy Hotel in London, 9th March 1976. He is holding a copy of his autobiography, entitled 'The Greatest - My Own Story'. (Frank Tewkesbury/Evening Standard/Hulton Archive/Getty Images)

Headshot of American boxer Muhammad Ali, former World Heavyweight Champion, shouting while wearing boxing gloves. (Hulton Archive/Getty Images)

Heavyweight boxing champion Muhammad Ali riding a horse near the Sphinx and the pyramids at Giza, Egypt, 1964. (Keystone/Hulton Archive/Getty Images)

American boxer Muhammad Ali with boxing manager Chris Dundee around the time of his World Heavyweight Boxing Championship fight against fellow American Sonny Liston at Miami Beach, Florida. Ali went on to win the match, securing his first world heavyweight title. (Harry Benson/Getty Images)

Muhammad Ali being restrained by his seconds as he rushes across the ring after his world heavyweight title fight victory over Sonny Liston, yelling to the ringside reporters 'eat your words'. (Central Press/Getty Images)

US boxer Muhammad Ali at his West End Hotel during his stay in London to fight Henry Cooper. (B. Potter/Express/Getty Images)

World heavyweight boxing champion Muhammad Ali in training at the Royal Artillery Gymnasium in London for his upcoming fight with British champion Henry Cooper, against whom he must defend his title. (Trevor Humphries/Getty Images)

American Heavyweight boxer Muhammad Ali in New York, dressed like a city gent in a suit and a bowler hat and carrying an umbrella. (Express/Getty Images)

Boxer Muhammad Ali stands outside his house with his three kids. (Getty Images)

US boxing heavyweight champion Muhammad Ali stands with her mother Odessa Grady Clay during a training session three days before the heavy weight world championship in Kinshasa. (STR/AFP/Getty Images)

World heavyweight boxing champion Muhammad Ali in training at the Royal Artillery Gymnasium in London for his upcoming fight with British champion Henry Cooper, against whom he must defend his title. (Keystone/Getty Images)

American heavyweight boxer Muhammad Ali poses for a portrait. (Getty Images)

Jack Nicklaus meets Muhammad Ali during the US PGA Championship at Valhalla Golf Club in Lexington, Kentucky, USA. (David Cannon/Getty Images)

American boxer Muhammad Ali relaxing after his world heavyweight victory over Sonny Liston. (Harry Benson/Express/Getty Images)

Heavyweight champion Floyd Patterson rubs heavyweight champion Muhammad Ali's shoulder as he says hello on April 01, 1993 at a gathering of boxers for the World Boxing Council awards ceremony. (Getty Images)

American heavyweight boxer Muhammad Ali in a one round non-title fight with 6 year old Patrick Power. Young Patrick is taking boxing lessons in order to combat bullies at home. (Keystone/Getty Images)

Former heavyweight boxing champion Mike Tyson speaks with boxing legend Muhammad Ali at the University of Nevada, Las Vegas student union ballroom. During the evening's program, which kicked-off Black History Month, Ali was honored for the contributions he made to the African-American community. (JOHN GURZINSKI/AFP/Getty Images)

Muhammad Ali posing with his belt in front of a sign 'Allah is the Greatest', in his apartment in Miami before his title fight with Sonny Liston for the World Heavyweight Championship. (Keystone/Getty Images)

Muhammad Ali of the USA relaxes at home in Deer Lake, Pennsylvania, USA. (Getty Images)

Heavyweight champion Muhammad Ali knocked out challenger Sonny Liston in the first round of their heavyweight fight on May 25, 1965, in Lewiston, Maine. The iconic image of Ali snarling over a fallen Liston has become one of the most well-known sports photos of all time.

The Beatles (from right), Paul McCartney, John Lennon, George Harrison and Ringo Starr pretend to be knocked out by a fake blow from Muhammad Ali.

Former heavyweight champ Muhammad Ali appears outside champ Joe Frazier's gym in Philadelphia, Jan. 28, 1971, prior to their iconic fight that would happen in March.

Joe Frazier, left, hits Muhammad Ali with a left during the 15th round of their heavyweight title fight at Madison Square Garden. The two undefeated boxers met March 8, 1971, in what became known as The Fight of the Century. After a taxing, physical match, Frazier was declared the unanimous winner.

Muhammad Ali puts on a show at the New York State Athletic Commission's office in New York City on Jan. 23, 1974, as he tries to force his way into the room where Joe Frazier was getting his pre-fight physical. Ali and Frazier had their rematch Jan. 28 at Madison Square Garden.

Joe Frazier sticks his chin out as Muhammad Ali points his fist toward him during a news conference in Malaysia. A young Don King, center, promoted the 1975 fight that would come to be known as the Thrilla in Manila.

Heavyweight champion Muhammad Ali connects with a vicious right to the head of challenger Joe Frazier. The third fight between the two was dubbed the Thrilla in Manila, and it ended prior to the 15th round when Frazier was unable to leave his stool. Boxing historians consider the bout one of the best of all-time.

Muhammad Ali toys with the finely combed toupee of television sports commentator Howard Cosell before the start of the Olympic boxing trials in 1972. Cosell rose to fame in sports broadcasting through his calls in Ali's big fights.

Muhammad Ali gets a bear-hug in the ring from Sammy Davis Jr. moments after beating Joe Bugner in Las Vegas. Entertainers like Davis frequently showed support to Ali throughout his career.

Muhammad Ali crushes Ken Norton during their 12-round bout in September 1973. Norton had stunned Ali six months prior, but Ali won the rematch in a split decision.

Muhammad Ali signs autographs for a swarm of fans in Queens, New York, prior to his rematch with Ken Norton.

Heavyweight Boxing champion Muhammad Ali holds a tennis racket over Tennis player Bjorn Borg July 1979 in USA. (Liaison/Getty Images)

Muhammad Ali sends world champion George Foreman down to the canvas in the eighth round of their WBA/WBC championship match in Zaire. Ali regained his heavyweight title on Oct. 30, 1974, in the "Rumble in the Jungle" after using a strategy coined the "rope-a-dope."

Actor Sylvester Stallone, star of "Rocky" and heavyweight champion Muhammad Ali clown around back stage after the Academy Awards show in 1977.

A younger, more attack-oriented Leon Spinks stunned Muhammad Ali in 1978 by defeating him in 15 rounds for the heavyweight championship. It was just the eighth career fight for the 24-year-old Spinks.

American swimmer Janet Evans looks on as Muhammad Ali lights the Olympic flame during the 1996 Summer Olympic Games opening ceremony in Atlanta. Ali, then known as a Cassius Clay, won Olympic gold in 1960 in Rome. (Michael Probst/AP)