Team Sky rider Nieve formed part of a large breakaway group before bravely taking the lead on the penultimate climb of the day with 33km to go.

He pulled away and held on to beat home Movistar rider Giovanni Visconti by 43 seconds for a first Giro stage win since 2011.

"It was a tough day out there," said Nieve.

"I knew that I needed to attack early, as if I didn't the peloton could easily have come back to us.

"I had a good feeling on the climbs and I managed to get down the descents without any issues - it went really well."

A group packed full of overall contenders finished 34 seconds later, with Costa Rican Movistar rider Andrey Amador duly overhauling Luxembourg's Bob Jungels for the leaders jersey.

The Quick Step rider finished 50 seconds off the pace after being dropped on the final climb.

Italy's 2014 Tour de France winner Vincenzo Nibali finished in third place on the day and duly moves third overall after claiming four bones second.

Spain's Alejandro Valverde lies joint fourth with The Netherlands' Steven Kruijswijk a further two seconds off the pace.

There will be more mountain tests to come tomorrow in a 210km 14th stage from Alpago to Corvara in the Dolomites.

At the Tour of California on the Women's World Tour, Twenty16–Ridebiker won the team time trial on the second day of racing.