It was a stage that almost had everything. Landa finally grabbing a win after two second places and that crash on stage 9, several attacks among the GC favourites, and now a new race leader - who himself appeared vulnerable - with just two stages remaining.
Landa launched his attack on the 20-rider break within the final 10 kilometres, crossing the line one minute and 49 seconds ahead of Rui Costa (UAE), Pierre Rolland (Cannondale-Drapac) a further six seconds behind in third.
"I’ve been fighting the last three or four days along with my team mates who have been doing really nice work," Landa said. "Finally today we got the win."
"It’s been difficult moments for the last month at the Giro. We started well, then we had the crash. We had to regroup. I feel very happy and emotional, especially as my family were here today.
"I saw everyone was looking at me. Fortunately I had my team mate Sebastian with me. He did some nice work in the first five kilometres to control the contenders."
While Quintana was able to put some time into Dumoulin and now leads the Dutchman by 38 seconds, several GC rivals put in attacks he was able to contain but not counter.
Thibaut Pinot (FDJ) beat home his GC rivals, gaining 11 seconds on the final climb with an attack from 7.5 kilometres out. Domenico Pozzovivo (AG2R) and Ilnur Zakarin (Katusha) also put in some punches and as Vincenzo Nibali (Bahrain-Merida) upped the pace, the Colombian looked to be in trouble.
But he dug deep on Nibali's wheel to contain the damage, eventually coming across the line ahead of the Italian by a couple of seconds.
Pinot's move saw him narrow his deficit to Nibali to just 10 seconds. Only one minute and 30 seconds now separates the top six places on the general classification.
You've got to have friends
Quintana's team mates Victor de la Parte and Winner Anacona worked hard from the bottom of the final Piancavallo climb to crack Dumoulin.
"We planned a good strategy, we delivered and we were able to make the race leader crack and remain close to the rest of GC contenders," Quintana said. "The impressive job by the whole team, I can't thank them enough."
"You've always got doubts about what wheel should you follow on that final climb. I knew I had to keep an eye especially on Nibali, but sometimes, it's up to other rivals to leave you behind and create gaps which are really difficult to close.
"We took a long shot at that descent with most of the team, and also pushed hard into the final climb. We just hope to keep this strong line tomorrow and defend ourselves well."
Did they or didn't they?
The fireworks started early. On the descent of the Passada climb, some 110 odd kilometres from the finish, Dumoulin - along with fellow Dutchmen Bauke Mollema (Trek-Segafredo) and Steven Kruijswijk (LottoNL-Jumbo) - was caught napping at the back of the peloton. Quintana, Nibali and Pinot pounced with some help from some team mates.
They gained a maximum advantage of around a minute and were just two minutes behind the original breakaway, but once the terrain levelled, it soon came back all together.
Broadcast commentators citing credible sources set Twitter alight as Quintana and Nibali were again accused of another dastardly attack on a nature-break loving Dumoulin. But the big man himself scorched those rumours after the race.
"I had bad legs from the start today," he said. "I made a rookie mistake earlier on in the stage and was sat at the back of the bunch. Other GC teams started to pull and the bunch split and caught me out.
"I needed to put in a lot of energy to get back across to the group which wasn’t ideal when my legs already weren’t great. In the final I tried to limit my losses which I think I did pretty well.
"The team were so strong and saved me a couple of times, I really have to thank them because without them it would have been a much worse day. I hope the legs are better tomorrow.”
The next 20-rider break including Landa, Rolland and Rojas, formed with some remnants of the earlier break, and escaped on the Sella Chianzutan climb. Movistar's Jose Joaquin Rojas and Jose Herrada were also part of this group but fell back later to help Quintana.