The Italian Etixx-Quick Step rider found himself in a 13-man breakaway group which established a five minute gap on the peloton, and was never caught.

Brambilla, who had never won a Grand Tour stage before today, attacked on the dirt roads of the Alpe di Poti in the final 25 kilometres of the 186km route.

With overall contenders languishing behind, he bravely descended to open up a gap back to compatriot Matteo Montaguti.

He eventually crossed the line 66 seconds clear of the Ag2r La Mondiale rider, with another Italian - Morena Moser of Cannondale - third a further 21 second back.

Other overall contenders rolled in shortly afterwards, with Alejandro Valverde of Spain, Vincenzo Nibali of Italy and Rigoberto Uran of Colombia sprinting home in the peloton.

Dutchman Tom Dumoulin had been unable to stay in contact, however, and fell to 11th place.

Brambilla now leads Ilnur Zakurin of Russia and Katusha by 23 seconds, with LottoNL-Jumbo Dutchman Steven Kruijswijk third, Movistar's Valverde fourth and Astana's Nibali fifth.

A rolling 40.5km time trial tomorrow could prove decisive ahead of a welcome rest day on Monday (May 16).