The 31-year-old Italian looked on course to win Olympic cycling road race gold until he crashed on a tricky corner 12km from the Copacabana finish in Rio.

He was taken to hospital, after which his Italy coach Davide Cassani said on Twitter: "Unfortunately @vincenzonibali has a broken collarbone."

It was a sorry end to what had been a promising race for the Italians, who had played their tactics to perfection.

They got three riders in a 10-man breakaway, after which Nibali struck out for home.

Only Colombia's Sergio Henao and Rafal Majka of Poland could go with him but after cresting the final climb 15 seconds clear of the rest with 15km to go, Nibali started to put the hammer down on a speedy descent.

Yet he and Henao came a cropper.

"Vincenzo was sitting on the kerb in silence. Words served no purpose, we looked at each other a moment but he was silent," said Cassani.

"We didn't say a word to each other, his morale was in tatters."

Cassani added: "We had ridden the perfect race, the lads were amazing but unfortunately a skid undid everything, it all went wrong."