To a country that invented the Hall of Fame and idolises sporting heroes, the names Tommie Smith and John Carlos are still pregnant with symbolism. The photograph of their proud-but-solemn "black power salute" on the podium at the Mexico Olympics in the summer of 1968 remains one of the defining images of a generation.

Yet exactly four decades after Smith and Carlos lifted gloved fists and bowed their heads in that dignified yet somehow menacing protest, their legacy has descended into a personal rivalry more bitter than anything they experienced on the athletics track.

Today, they refuse to speak. They will not appear together in public. In a long-running feud, each has written an account of 1968 that contradicts the other; each has attempted to take credit for the now-legendary protest; and each has publicly called their former comrade a liar.

As a result, the 40th anniversary of Carlos and Smith's snub to "The Star-Spangled Banner" is overshadowed by uncertainty and unlikely to be formally celebrated at this summer's Olympics in China...