The Jumbo-Visma rider had put himself into the top-10 in the opening week and was just 13 seconds outside of the race lead as the race went into the first real mountains on stage eight.
But on the road to Loudenvielle, Dumoulin felt he wasn’t strong enough to stay with the leaders and instead sacrificed himself to ride for Primož Roglič.
Speaking on the first rest day of the Tour Dumoulin, winner of the 2017 Giro d’Italia, said: “For myself I would have liked more of course. I came here with the goal to win the Tour de France with the team and also with the idea of me being the one doing it.
“That disappeared over the last weekend. Luckily Primož is on a great level and is in the yellow jersey now so I think he’s the best of the race right now and we hope to defend it until Paris.”
Dumoulin has slipped back to 14th overall as the race heads into the second week, 3-22 off the lead, while Roglič leads by 21 seconds over Egan Bernal (Ineos Grenadiers).
Jumbo-Visma have been the dominant team in this year’s Tour, winning three stages so far with Roglič and Wout van Aert.
While the Dutch squad had planned to race for both Dumoulin and Roglič, they were forced to improvise when mountain domestique Sepp Kuss lost touch on stage eight.
Then on the Col de Peyresourde, Dumoulin radioed in to tell his team-mates he wasn’t feeling good and that he’d ride for Roglič.
After putting in his turn, Dumoulin lost two minutes on the stage and then lost more time the following day.
The 29-year-old said: “For me personally I would like to have better legs and it didn’t happen. What you hope and what happens, that’s two different things.”
Dumoulin said he hasn’t been feeling his best in the first week, but he hopes to find his form in the final third of the race.