There had been drama earlier in the day as Dumoulin was caught on the wrong side of a split in the peloton in the first 60km, but when that had been neutralised it was clear that it was all going to come down to the final climb to Piancavallo.
Mikel Landa had been part of a large group that had gone clear with around 90km to race, building up an advantage of more than 10 minutes.
In the break were: Clément Chevrier (Ag2r La Mondiale), Pello Bilbao (Astana), Nicola Boem (Bardiani-CSF), Gregor Mühlberger (Bora-Hansgrohe), Pierre Rolland (Cannondale-Drapac), Maciej Paterski (CCC Sprandi Polkowice), Tobias Ludvigsson (FDJ), Evgeny Shalunov (Gazprom-Rusvelo), José Herrada (Movistar), Dries Devenyns (Quick-Step Floors), Daniel Teklehaimanot (Dimension Data), Jurgen Van den Boreck (LottoNL-Jumbo), Rui Costa (UAE Team Emirates), and Ilia Koshevoy (Wilier-Selle Italia).
Four kilometres further up the climb, Landa had opened his lead to more than a minute, but all the action was coming from behind, where Dumoulin found himself without a team-mate for the first time as Geschke finally cracked.
The Dutchman was beginning to look a little stronger, but then the attacks started from the front group as Thibaut Pinot launched an acceleration with 7.5km to go. Pinot had looked strong on stage 18, and no one was able to follow, quickly opening a significant gap.
Visconti continued to work on the front of the group, but most of the GC contenders looked dead on their feet, struggling to hold the Italian's wheel.
1. Nairo Quintana (Col) Movistar, in 85-02-40
2. Tom Dumoulin (Ned) Team Sunweb,at 38 secs
3. Vincenzo Nibali (Ita) Bahrain-Merida, at 43 secs
4. Thibaut Pinot (Fra) FDJ, at 53 secs
5. Ilnur Zakarin (Rus) Katusha-Alpecin, at 1-21
6. Domenico Pozzovivo (Ita) Ag2r La Mondiale, at 1-30
7. Bauke Mollema (Ned) Trek-Segafredo at 2-48
8. Adam Yates (GBr) Orica-Scott, at 6-35
9. Bob Jungels (Lux) Quick-Step Floors, at 7-03
10. Steven Kruijswijk (Ned) LottoNl-Jumbo, at 7-37
How it happened
Kruiswijk was also dropped as the gradient ramped to 14 per cent with nine kilometres to go, blowing up more spectacularly than Dumoulin and going straight back past the pink jersey.
General classification after stage 19
By the line Dumoulin had lost 1-09 to Quintana, meaning that the Colombian moved into pink by 38 seconds, with Nibali third at 43 seconds and Thibaut Pinot fourth at 53 seconds.
The racing was fierce, with both groups riding at high speed down the wide valley roads, and slowly but surely the pink jersey group clawed its way back to within 20 seconds.
Mollard was quickly dropped, leaving Sanchez to plough on alone opening a few more seconds on the steep early slopes. However the Spaniard was caught and dropped by former world champion Rui Costa, who was then joined by Landa.
That move meant that Vincenzo Nibali's podium place was under threat, and the Italian was forced to react, going for what looked like a tired acceleration. It wasn't enough to put many riders in trouble, with Ilnur Zakarin even having enough in his legs to launched a short-lived counter-attack.
Those accelerations opened the gap back to Dumoulin out to 31 seconds, putting the Dutchman out of the virtual maglia rosa as Visconti and Rojas dropped back from the break to inject some pace for their team-mates.
11. Thibaut Pinot (Fra) FDJ, at 8-09
12. Domenico Pozzovivo (Ita) Ag2r La Mondiale, at 8-15
13. Ilnur Zakarin (Rus) Katusha-Alpecin, at same time
14. Bob Jungels (Lux) Quick-Step Floors, at 8-21
15. Adam Yates (GBr) Orica-Scott, at same time
16. Nairo Quintana (Col) Movistar, at same time
17. Bauke Mollema (Ned) Trek-Segafredo, at 8-23
18. Vincenzo Nibali (Ita) Bahrain-Merida, at same time
22. Tom Dumoulin (Ned) Team Sunweb), at 9-30
30. Steven Kruiswijk (Ned) LottoNL-Jumbo, at 10-41
However Zakarin was more lively, attacking with Pozzovivo in his wheel, both men looking to move themselves into podium contention and chase down Pinot.
For a long time he seemed to be keeping the gap to the group containing Quintana and Vincenzo Nibali (Bahrain-Merida) at less than the 31 seconds he needed to hold on to pink, but as the accelerations started in the final three kilometres the gap started to grow.
The 19th stage of the 2017 Giro d'Italia saw another fast start, with a 14 rider move going clear on the first climb of the day.
Collaborating with his fellow countrymen Kruiswijk and Bauke Mollema, Dumoulin steadily reeled in the Quintana group on the climb, with one final effort from Yates needed to two groups back together with around 90km still to race.
Six men went away on the climb in Pello Bilbao and Luis Leon Sanchez (Astana), Pierre Rolland (Cannondale-Drapac), Evgeny Shalunov (Gazprom-Rusvelo), Sebastian Henao (Team Sky) and Rui Costa (UAE Team Emirates), who were able to open a sizeable gap of more than six minutes.
Winner Anacona (Movistar) and then Franco Pellizotti (Bahrain-Merida) were doing all the damage, and for the first time in this Giro d'Italia the Team Sunweb leader looked in real trouble.
Rui Costa took second on the stage, out-sprinting Pierre Rolland who had joined him midway up the climb, before eyes turned back to the battle for the pink jersey.
Giro d'Italia 2017, stage 19: San Candido/Innichen to Piancavallo (191km)
All that action meant that the break was caught, but there was still some chasing to do for the maglia rosa.
But then it was the Portuguese rider's time to suffer, and with 10km to go Landa went solo.
He had team-mate Simon Geschke for company, but the gap continued to grow, the group of his rivals inching away from the struggling Dumoulin.
By the finish they had the Frenchman in sight, but he was still able to gain time, crossing the line 8-09, followed a few seconds later by the rest of the GC contentenders.
The only man missing was Dumoulin who was fighting with his bike through the final kilometres, pedalling squares as he fought to the line, coming home at 9-30, losing more than a minute and the pink jersey in the process.
Pellizotti was still plugging away on the front of the Quintana/Nibali gorup, but Dumoulin still had them within sight, occasionally glancing down at his power meter as he had the gap locked at around 20 seconds.
Meanwhile, in the main group, Dumoulin was also on the move, unfortunately in the wrong direction as he struggled to hold the wheels.
By the intermediate sprint after 47.3km their lead had grown to slightly more than four minutes before drama ensued behind.
But Bahrain-Merida weren't giving up just yet, and as the second-category climb Sella Chianzutan started with 97km remaining Kanstantin Siutsou went to the front to raise the pace once more.
After the frantic first half of the stage there was then an easing of the pace among the GC contenders as they slowed to catch their breath. This gave an opportunity not only for the rest of the peloton to latch on to the back of the group, but also for some attackers to go off the front.
On the approach to the final climb to Piancavallo Sanchez attacked with Mollard, gaining 30 seconds over the rest of the escapees as they went on to the final climb with 15km remaining.
Nearly 10 minutes later the peloton started the climb, with Movistar setting the a fierce pace and immediately putting Dumoulin under pressure. The pink jersey looked in dire straits, yo-yoing off the back of the group as he struggled to hold the wheel.
Nairo Quintana (Movistar) moved into the pink jersey as Tom Dumoulin (Team Sunweb) was dropped early on the final climb on stage 19 of the Giro d'Italia, with Mikel Landa (Team Sky) winning the stage.
The Spaniard had finished second in two-up sprints twice so far in the race, but was not going to risk making the same mistake for a third time, going solo early in the climb and taking victory by nearly two minutes to rescue Team Sky's race after having had their GC hopes ruined by the motorbike crash on stage nine.
At around 50km into the stage there was a split in the bunch as Movistar and Bahrain-Merida moved to the front of the peloton to raise the pace on a descent, catching out the pink jersey of Tom Dumoulin who was caught riding too far back in the group, with a Team Sunweb sports director reporting that the move was made while Dumoulin was returning after a natural break.
The gap between the two groups quickly grew to a minute before Sunweb, Orica-Scott (working for Adam Yates), and LottoNL-Jumbo (working for Steven Kruiswijk) got organised in the chase while all of the other GC contenders were on the right side of the split.
They were joined by 12 more riders, Giovanni Visconti (Bahrain-Merida), Clément Chevrier (Ag2r La Mondiale), Nicola Boem and Lorenzo Rota (Bardiani-CSF), Rudy Molard (FDJ), José Herrada and José Joaquin Rojas (Movistar), Ruben Plaza (Orica-Scott), Eros Capecchi (Quick-Step Floors), Mikel Landa (Team Sky), Matteo Busato and Ilia Koshevoy (Wilier Triestina), to create an 18-strong front group with a lead of seven minutes going into the final 50km.
That gap only got bigger as the peloton slowed and swelled, going up to 13 minutes at one point.
At the front of the race there was a moment for Mikel Landa to savour, as the blue jersey took a superb stage victory to rescue Team Sky's Giro d'Italia and make up for his two previous stage wins.
1. Mikel Landa (Esp) Team Sky, in 4-53-00
2. Rui Costa (Por) UAE Team Emirates, at 1-49
3. Pierre Rolland (Fra) Cannondale-Drapac, at 1-54
4. Pello Bilbao (Esp) Astana, at 2-12
5. Sebastian Henao (Col) Team Sky, at 3-06
6. Evgeny Shalunov (Rus) Gazprom-Rusvelo, at 3-51
7. Luis León Sanchez (Esp) Astana, at same time
8. Matteo Busato (Ita) Wilier Triestina,at 5-05
9. Lorenzo Rota (Ita) Bardiani CSF, at same time
10. Ilia Koshevoy (Blr) Wilier Triestina, at 6-44
Egan Bernal: Everything will depend on how my back responds
Egan Bernal says his Giro d’Italia will depend on the back problems he has been struggling with in recent years.
By Alex Ballinger •
Ineos Grenadiers reveal the full team for the Giro d'Italia 2021
Ineos Grenadiers have revealed their full squad for the Giro d'Italia 2021, with Egan Bernal leading the charge.
By Alex Ballinger •
‘Simon can learn to stand on his own two feet,’ says BikeExchange sports director after departure of Adam Yates
Simon Yates can learn to ‘stand on his own feet’ after the departure of his brother from Team BikeExchange, according to sports director Laurenzo Lapage.
By Alex Ballinger •
'I'm stronger than I’ve ever been right now' says Dan Martin going into Giro d'Italia 2021
Dan Martin is set to lead his Israel Start-Up Nation squad into battle for the overall title at the Giro d'Italia 2021 and he comes into the race with a lot of confidence
By Tim Bonville-Ginn •
Dylan Groenewegen says he will never put Tour of Poland crash behind him completely
Dylan Groenewegen says he will never put the Tour of Poland crash behind him completely.
By Alex Ballinger •
Dylan Groenewegen will race Giro d’Italia as UCI ban ends
Dylan Groenewegen will return to racing at the Giro d’Italia, his first race back after he was banned by the UCI.
By Alex Ballinger •
Thibaut Pinot opts out of Giro d'Italia as he would just 'unnecessarily suffer'
The Frenchman's back problems persisted at the Tour of the Alps and no date for his return to racing has been set
By Jonny Long •
Is this the Ineos Grenadiers line-up for the Giro d'Italia 2021?
Here are the other riders rumoured to be accompanying Egan Bernal to the Italian Grand Tour
By Jonny Long •