Dumoulin took a stunning victory in the men's individual time trial at the Bergen world championships on Wednesday, beating Primoz Roglic (Slovenia) by 57 seconds and Chris Froome (Great Britain) by 1:21. He was also part of Team Sunweb's team time train winning squad of six and has a chance of a third world title in Sunday's elite men's road race.
The Dutchman has enjoyed a remarkable season, winning the Giro d'Italia in May, the BinckBank Tour in August and then the time trial title. Dumoulin will be 27 in November and is clearly nearing the peak of his career and physical ability.
Dumoulin's rare combination of Grand Tour ability and world-class time trial skills makes him Froome's biggest rival for the 2018 Tour de France. However, Dumoulin and his Team Sunweb squad have always selected their goals carefully as part of a long-term development plan, preferring a lighter racing programme to lofty goals. He opted to not ride the Vuelta a Espana after his success in the Giro d'Italia, knowing a selective race programme and specific blocks of training could give him a peak of form for the world championships.
His success of 2017 has, in turn, boosted his self-confidence.
"I think my abilities are quite wide; I can apparently win a Grand Tour and the time trial championships. Until now one hasn't bitten the other and I'll probably be able to do both in the future," Dumoulin explained.
"I focus on my climbing and Grand Tours in the first part of the season and then worry about my time trial skills in the second part of the season. I love time trialing, so I'll probably do that in the future. Targeting Grand Tours is somewhat more stressful but it's nice if you can win them. It's all a matter of focusing on the right things."
After going close to victory in the 2015 Vuelta a Espana and then winning this year's Giro d'Italia, ahead of Nairo Quintana and Vincenzo Nibali, it seems logical that Dumoulin will step up again and finally challenge for overall victory at the Tour de France and try to stop Froome taking a fifth victory. However, Dumoulin is keeping his plans close to his chest until later in the winter.
"I don't know about next year yet, we haven't seen the routes of the Giro d'Italia, the Tour de France to the Vuelta a Espana. They're not on my mind yet," he suggested.
"So far my career has been getting better every year. I'm having a very special year, which probably not happen again quickly. I'll just keep on working hard and hope that with a nice mindset and nice goals, that I can achieve even more in the coming year.
"My success has given me a feeling that I was capable of more than I thought. Before the Giro, I didn't think it was possible to win it, at least not this year. I thought top five would have been nice. Then I won it and it was amazing. It gave me a lot of confidence for other races after that."