Dumoulin finished second to Froome in the Giro d'Italia at 46 seconds on May 27, and announced to his team that night that he would try to race for the overall in the Tour too this July.
It will be the first time Dumoulin will race for the overall in the Tour, having won the Giro title last year.
He said that he was not fatigued at all after the three weeks in Italy battling Chris Froome (Sky) and Simon Yates (Mitchelton-Scott).
"Actually, I feel very fresh," Dumoulin told De Telegraaf from a training camp in the Alps.
"After the Giro d'Italia, I consciously rested more than I would normally do. In the first nine days, I hardly even touched my bike."
Dumoulin surprised followers and himself with his Vuelta a España breakthrough in 2015. He nearly won the race overall, but crumbled under pressure from Team Astana in the final mountain day. In 2016, he raced the Tour but for stage wins, taking one in the mountains and the time trial.
The 2017 Giro was the first Grand Tour he started with the aim of overall victory. In 2018, with the race featuring more time trial kilometres than the Tour, he returned to do the same, winning the opening time trial, wearing the pink jersey and constantly threatening leaders Yates and then Froome.
Dumoulin, unlike Froome, has raced since the Giro ended in Rome. He participated in the three-day Dutch Hammer Series near his home in Limburg.
After some rest and a training camp, he is ready for the Tour. "I've never been so fresh two weeks after a Grand Tour," he said.
The Dutchman is one of several favourites with Sky's Froome and Geraint Thomas, the Movistar trio of Mikel Landa, Nairo Quintana and Alejandro Valverde, Romain Bardet (Ag2r La Mondiale), Rigoberto Urán (EF Education First-Drapac), and Vincenzo Nibali (Bahrain-Merida).
Of the big stars, only Froome and Dumoulin will complete the double. Thibaut Pinot (Groupama-FDJ), who suffered from dehydration and fever in the Giro's final mountain day, cancelled his planned Tour ride last week.
"I had in mind that I really wanted to race the double since the winter," Dumoulin continued.
"If things go badly in the Tour, it's nice that I know that I have shown myself well in the Giro. I am very happy and proud of my performance in that race. No-one can take that feeling away from me.
"Anyway, I'll be racing for the overall in the Tour. I know it's going to be a physical and mental fight. It is not that I'm racing there with the idea that I have already had a good grand tour [in the Giro]. I am going to do everything to finish high up in the Tour too."
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