George Foreman says the legendarily nasty public feud between Muhammad Ali and Joe Frazier was actually friendly behind closed doors ... telling TMZ Sports the two men secretly loved each other.
The war between Ali and Frazier is well-known -- Ali called him names like "gorilla" and "Uncle Tom" -- which reportedly wounded Frazier until his death in 2011.
In fact, Frazier famously expressed his distaste for Ali in a 1990 interview -- "I hated Ali. God might not like me talking that way, but I hated that man.