On March 8, 1971, Muhammad Ali and Joe Frazier fought in what was billed as the "Fight of the Century" at Madison Square Garden. LIFE has put together a gallery of photos taken by a 24 year-old staff photographer named John Shearer 40 years ago; the majority of his photos were never published until now. There's a look at Joe Frazier and his R&B group, "The Knockouts," as well as this shot of Ali sparring at a Miami grocery store a few weeks before the fight. It's an amazing glimpse into the earlier years of these two men, who now both must cope with the consequences of their careers. Take a look.

NEVER-SEEN: Ali vs. Frazier, 1971 [LIFE]