The Nippo-Vini Fantini-Faizanè rider held off Germany's Pascal Ackermann of Bora-Hangrohe and fellow Italian Simone Consonni of UAE Team Emirates at the end of the 222 kilometres route from Valdaora/Olang to Santa Maria Di Sala, crossing the line in a time of 4 hours 56min 04sec.

He had earlier broke clear of the peloton with Germany's Nico Denz and Italy's Mirco Maestri, both of whom faded as the main group bridged the gap in the final 200 metres.

"I can’t believe what just happened," Cima, in his second year as a professional, said.

"I’ve spent so many kilometres in breakaways during this Giro. 

"I thought I’d never make it but I’ve won today. 

"It’s insane. 

"It’s the dream of a lifetime."

Ecuador's Richard Carapaz of Movistar Team finished safely in the peloton to retain the general classification lead.

His overall time now stands at 79:44:22.

Nearest challenger, Italy’s Vincenzo Nibali of Bahrain-Merida, is 1min 54sec back, while third-placed Slovenian Primož Roglič of Team Jumbo-Visma is a further 22 seconds behind. 

"It’s been a quiet stage but a long one, intense at the beginning only," Carapaz said.

"I’ve had a good support from my team again. 

"Tomorrow will be an important test but I’m confident to keep the Maglia Rosa."

The 21-stage race is due to continue tomorrow with a 151km route from Treviso to San Martino di Castrozza. 

Action is scheduled to conclude with a time trial in Verona on Sunday (June 2).