The Movistar rider attacked out of an elite group in the closing kilometres of the day's final climb, the Monte Terminillo, crossing the line to snag the mountaintop victory and the GC lead just as he had done two years prior on stage 5 of the 2015 edition of the race.
Sky's Geraint Thomas finished second, 18 seconds behind Contador, with Orica-Scott's Adam Yates claiming third on the stage – 24 seconds down – while rising to second overall.
