Colombian climber Nairo Quintana completed an epic day of racing on the Giro d'Italia by claiming victory on a controversy-hit 16th stage and the race leader's jersey from compatriot Rigoberto Uran.
Quintana's hopes of competing for the overall title this year suffered a blow when he tumbled down the standings to 3min 29sec behind Uran after the first two weeks of racing.
But on the first of several gruelling days in the mountains in this final week, the Movistar rider took command of the race Uran and, notably Australian Cadel Evans, ultimately failed to follow Quintana's wheel on a rain-hit descent of the Stelvio climb.
"I did the last climb at my own rhythm but I gave it everything I had," said the 24-year-old Colombian.
"Since the start of the season, I think I've shown my runner-up place at the Tour de France (in 2013) was no fluke.
"In this Giro I've encountered a few problems but I've never lost hope. The team have been right behind me and kept my confidence intact."
With three tough climbs on the menu Uran was always at risk of being put under pressure by the more proficient climbers in the peloton.
But the heavy rain and freezing conditions which prevailed over the first two climbs -- the Galvia (16.5 km) and the Stelvio (21.7 km) -- did little to help the overnight leader's bid either.
Sky rider Dario Cataldo started hostilities when he attacked from a small chase group on the way to the summit of the Stelvio, whose 2758 metres summit is the highest point of this year's race.
He came over the summit, the road flanked by walls of snow several metres deep, with a 20sec lead on two or three stragglers with Hesjedal and Quintana among another group that had managed to pull away from Uran's main peloton on the way to the summit. It later emerged their move had been controversial.
Uran's Omega-Pharma team were among those who interpreted an announcement by race organisers via race radio to mean the Stelvio descent would be 'neutralised' -- effectively not raced -- because of the poor conditions.
Organisers later claimed they had simply announced they were placing a motorbike rider, with a pillion passenger waving a red flag, at the front of the race to warn of any dangers on the road ahead.
Several teams complained after the stage, pointing to a Tweet posted by organisers, and later erased, that they had understood the race would be "neutralised".
But race director Mauro Vegni hit back: "There was never any question of the race being neutralised."
Quintana claimed he "did not attack" on the descent and added: "I don't understand the reasons" behind the controversy.
"It was raining a lot, I couldn't see" the red flag, "All I know is he was supposed to warn us about any dangerous bends."
Riding conditions worsened on the descent but Quintana, known more for his skills going up mountains, held his nerve as the chasers kept solo leader Cataldo in their sights and left plenty of nervous chasers in their wake.
Cataldo began the final, 22 km climb to the finish line with a 1:14 lead on Quintana, Rolland and Hesjedal and a three-minute cushion on the pink jersey holder.
But the Italian was soon overhauled as Quintana, Rolland and Hesjedal pressed on together until they steadily dropped back from the Colombian's back wheel.
Hesjedal came over the finish line 7secs in arrears while Uran trailed home 4:11 off the pace and Evans crossed nearly 30secs later.
Quintana, the runner-up at last year's Tour de France, now leads Uran by 1:41 in the overall standings although the day's biggest loser was Evans, who has dropped from second overnight at 1:03 to third overall at 3:21.
Wednesday's 17th stage is a 208 km trek over rolling terrain from Sarnonico to Vittorio Veneto.