Meanwhile, Britain's Geraint Thomas suffered a massive blow to his chances of winning the general classification, finishing more than 12 minutes behind the lead.

Portugal's João Almeida had a safely solid day to take the pink jersey from Italy's Filippo Ganna in the general classification, just ahead of Caicedo.

The 150 kilometre route from Enna to Mount Etna marked the first day that the race would head into the mountains.

It all started with an early breakaway pack that would determine the winner of the race which was started by Belgium's Victor Campenaerts and the United States' Lawson Craddock, with the pair quickly being joined by a further four riders.

With 136km to go, Caicedo joined the front pack with Danish cyclist Mikkel Bjerg and the eight riders would work hard to pull out a gap of almost five minutes at the halfway mark.

This gap would continue to sit around five minutes with 40km left, with the peloton facing a more immediate issue shortly after when a dog wandered into the army of cyclists.

Luckily, riders managed to spot the pooch in time and slowed down to avoid a collision.

From there, the pace began to pick up and the peloton pulled the gap back to 3min 45sec at 29km to go - while Croatian Josip Rumac and Italian Francesco Romano at the same period had been dropped from the front pack, reducing its number to six.

Britain's Matt Holmes and Italy's Giovanni Visconti were the other two names in the break with Caicedo, Bjerg, Campenaerts and Craddock.

Britain's Thomas suffered a crash early in the stage and found himself falling off the pace of the peloton with 25km to go, being kept company by the time trial specialist and general classification leader Ganna of Italy who looked ready to concede his overall lead on the mountains.

As the peloton hit the Mount Etna climb with 16km to go, there was a 3min 30sec gap between them and the break, who had just dropped Craddock.

Moments later, Holmes aimed to make a further break, but was covered by Caicedo and then by Visconti as the Briton was forced into chasing rather than leading.

Soon, the struggling Campenaerts and Holmes were caught by the peloton along with Bjerg at 10km leaving just two at the front with a two-minute gap.

With just 5km left until the line, Visconti made an attempt to leave Caicedo, but the Ecuadorian responded immediately and surged past his rival and dropping him quickly.

Holding more than a minute over the peloton, there was still time to catch Caicedo, but that looked less likely when the gap increased to 1min 40sec with only 1.5 miles left to race.

Despite breaks from the peloton occurring further back, the Ecuadorian was rewarded for his brave effort, winning by 21 seconds ahead of Visconti.

"This is a dream come true," said Caicedo.

"We planned to go in the break and go for it, I felt good in some moments but bad in others and was going to give up hope.

"Then when Visconti attacked I realised I felt good and attacked, myself.

"I've worked hard for this and I have to thank the guys in the team, they helped me so much."

Belgium's Harm Vanhoucke was 30 seconds behind in third after emerging as the top finisher from the peloton, ahead of Dutch rider Wilco Kelderman who was 39 seconds behind.

Denmark's Jakob Fuglsang led Poland's Rafał Majka, Italy's Vincenzo Nibali, Spain's Jonathan Castroviejo and Italy's Domenico Pozzovivo in fifth, 51 seconds behind, while The Netherlands' Steven Kruijswijk rounded off the top 10, 56 seconds behind Caicedo.

Almeida currently sits in the pink jersey position, but no time separates him and Caicedo.

The pair then have a 37 second lead ahead of Spain's Pello Bilbao, with Kelderman 42 seconds behind in fourth and Vanhoucke, Nibali and Pozzovivo all within a minute of the lead.

Sicily's final stage of this year's Giro is scheduled to take place tomorrow from Catania to Villafranca Tirrena over a 140km route.