BARDONECCHIA — Britain's Chris Froome produced an astonishing lone attack to roar into the overall Giro d'Italia lead on Friday, winning stage 19 with a performance that will go down in cycling folklore.

The Team Sky rider started the 185km stage from Venaria Reale to Bardonecchia more than three minutes back in fourth place on the overall standings but finished 40 seconds ahead after leaving his rivals in his tracks with a searing burst of pace 80km from home on the Colle delle Finestre.

It looked a huge gamble but Froome quickly pulled away and powered over the penultimate Sestriere climb before ascending the 7km Jafferau to the finish and slip into the Maglia Rosa for the first time in his glittering career.

He will go into Saturday's final mountain stage with a lead over second-placed reigning champion Dutchman Tom Dumoulin — an unthinkable situation 24 hours earlier.

Long-time leader Simon Yates, who started the day three minutes and 22 seconds ahead of compatriot Froome, ended the stage with his Giro hopes in tatters after blowing up and finishing 35 minutes adrift in the general classification.

Dumoulin began the day in second place, nearly three minutes ahead of Froome, but was left desperately trying to minimize the damage inflicted by the Briton on the final climb, although he received precious little help from the chasers.

The Dutchman failed to even earn any time bonuses as he was overtaken in the final 500 meters, finishing fifth, three minutes and 23 seconds behind Froome who did take bonuses.

Frenchman Thibaut Pinot is third overall, four minutes back, after attacking an exhausted Dumoulin in the sprint to the line.

Froome, who began the race with an anti-doping case still hanging over him and seemingly off the pace after some minor crashes in the first week, is now favorite to become the first Briton to win the Giro.

"We knew it would take something really special today to first of all get rid of Simon and get away from Dumoulin," Froome, who is bidding to hold all three Grand Tours simultaneously having won last year's Tour de France and Vuelta Espana, told Eurosport.

"To go from fourth to first, I knew that wasn't going to happen on the last climb. The Finestre was the perfect place to do it because the gravel roads remind me of riding on the roads back in Africa.

"I just felt it was now or never. The legs are feeling good and I've been feeling better and better as the race has gone on. Hopefully we can finish it off tomorrow."

Victory is not yet guaranteed though with Saturday's 183km stage to Cervinia featuring three first category climbs. Team Sky boss Dave Brailsford said that even when Froome lost time in the first two weeks, they stuck to their plan.

"The plan was always to get to this point and win the race in this block and we just thought let's put it on the line and see what happens," he said. "You can have the best plan but it takes the individual and the mentality to deliver it." — Reuters