Dumoulin won by more than 31 seconds so that he is crowned as the first ever Dutch winner of the Giro d’Italia.
Nairo Quintana retained the overall lead but, with the first four riders within 53 seconds of the Colombian, the three-week race is set for a dramatic finale.
Dumoulin remains in a strong position with the final day time trial on the cards, but Quintana has one more mountain stage – including the Monte Grappa – to try and open up the biggest possible lead.
European Council President Donald Tusk on Friday urged Group of Seven leaders to stick firmly to their sanctions policy on Russia over the Ukraine crisis.
Tejay Van Garderen clinched his maiden Grand Tour win on Stage 18 of the Giro d'Italia.