It took almost three weeks in the Giro d'Italia, but the knives finally came out in the Dolomites.
The Dutchman in pink responded to a Quintana/Nibali joint attack and refused to work with them when others went.
Thibaut Pinot (FDJ) gained 1-02 minutes, and moved within 30 seconds of the podium with three days to race, while the duo stalled and Dumoulin gestured to them to pull in the final kilometres.
"I hope that Nibali and Quintana will lose their podium spots because of only focusing on me," Dumoulin said.
"I don't understand why the three of us didn't work together. They also lose their podium spot if the other classification contenders get closer.
"Pinot is much better in the time trial than Nibali and Quintana normally, definitely in a flat time trial. Like I said, if they only focus on me it would be nice if they lose podium spot in Milan."
Colombian Nairo Quintana launched an attack on the Passo Gardena high in the Dolomite Mountains. Instead of a steady chase, Italian two-time Giro winner Vincenzo Nibali jumped and joined Quintana and the two worked together to ditch Dumoulin.
Dumoulin bridged at the top at 85.3 kilometres to race and when the race reached the final kicks to Ortisei, launched attacks of his own on his ragged looking rivals.
"I don't care what Tom said, I think he is being cocky, he's talking too much, I'd never talk like that," Nibali said at his team bus.
"He's shown he's very strong in the race but he's talking too much. He could also lose the podium because nothing is sure in this Giro d'Italia. Except, for sure, we won't accompany him all the way to Milan.
"He's got to keep his feet on the ground, does he know what karma is?"
"And then he calls me cocky?" Dumoulin responded. "Yeah they are also very strong words from his side. I was very friendly the whole Giro to everyone, and I think Nibali is for sure here to win the Giro, and I was not happy with how they rode they were only trying to make me lose and not… that's his choice."
Dumoulin still holds his top spot, but second through fifth place compacted with Pinot and Russian Ilnur Zakarin (Katusha-Alpecin) riding clear on Thursday's stage.
Dumoulin leads Quintana by 31 seconds and Nibali by 1-12 minutes. Pinot is now at 1-36 and Zakarin at 1-58.
"He was telling us to close the gap to the other riders who were attacking who were back on the classification," Quintana said.
"He didn't want them to take too much time. We left the responsibility on him, and in the end, he didn't take time on us, either.
"We did what we could as a team, as we had hoped. Sure, we wanted more, but [Dumoulin] responded well. We made a good stage, it was very fast all day, and tomorrow will be another chance."
The 19th stage ends with a hard final climb up to Piancavalo and a rolling difficult stage with a final kick to Asiago on Saturday.
On Sunday, it swings in Dumoulin's favour with a 29.3-kilometre time trial.
"Clearly very hard mountains days are again coming up," Dumoulin said.
"So I will try to fight as hard as I can and try to follow Quintana and Nibali and the other guys …"
"I was feeling good I was never in stress when they attacked today. I knew I had the legs to follow if I need to. Yeah, at the end I had the legs and could attack them."
Dumoulin knows how fast the race can slip away. In 2015, just developing into a Grand Tour rider, he led the Vuelta a España and on the final day in the mountains, slipped from first overall to sixth.
"I do believe in myself. I also have doubts, but I try to look at it from the positive side. I lost it in the Vuelta because maybe I was thinking a little negative also, I started to get tired, it's very hard to stay positive, but until now it's been good."
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