Just minutes after race leader Steven Kruijswijk ploughed into the side of a bank of snow, the television cameras showed Zakarin laying well away from the road next to a river on the descent of the Colle dell'Agnello.
While cameras didn't capture the crash, the sight of Zakarin laying so far off the road prompted many to fear the worst.
Medics were quickly on the scene, as was the Katusha team car to administer help, by which point the Russian rider was seen to be moving his legs. A tweet from Katusha said the injury could be a broken collarbone and that Zakarin would be taken to hospital.
Zakarin had sat fifth in the general classification after stage 18, nearly five minutes down on race leader Steven Kruijswijk, but was forced to abandon after the crash.
Kruijswijk himself found himself over a minute down on rivals Vincenzo Nibali and Esteban Chaves on the long descent after hitting a bank of snow hard and damaging his bike.
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