As anticipated, Dumoulin was a class above the rest of the Vuelta field in Wednesday's race against the clock, finishing 1min 4sec ahead of Maciej Bodnar (Tinkoff-Saxo) in a time of 46min 1sec, with Alejandro Valverde (Movistar) third at 1min 8sec.
The stage was always going to be about what Dumoulin could do in the time trial and by how much after 16 demanding stages, and he did not dissapoint, riding not only to victory, but the race lead.
However, Fabio Aru (Astana) surprised everyone with with a solid ride of his own, coming 10th on the stage 1min 53 sec back. This keeps Aru in second on GC, just three seconds behind Dumoulin and in a prime position to win in Madrid with four demanding, lumpy stages ahead.
It seems Dumoulin is ready to fight for the Vuelta, though
“I am very happy with this victory and with taking the red jersey again,” Dumoulin said. “My legs were great. Even now I am still feeling relatively fresh.
"When I finished, I found out that I had Aru at three seconds — that’s very close, that’s going to be a hell of a fight in the coming days," he added. "There are some important competitors close behind me in the GC, and I hope they will attack each other as well."
Rodriguez, Majka fall behind; Valverde surprises
The time trial saw a wholesale reshuffling of the overall top ten as the chrono men came to the fore.
Joaquim Rodriguez (Katusha) was one of the biggest losers on the day, finishing more than three minutes behind Dumoulin on the stage. He is now third on GC, 1min 15 sec back.
Rafal Majka droppped to fourth after an equally uninspiring effort against the clock.
Valverde moved upwards into sixth place overall after a well dosed effort, while Nairo Quintana (Movistar) put in a solid ride to move up to fifth, 2min 53sec behind Dumoulin.
Esteban Chaves (Orica-GreenEDGE) lost a place despite a quality ride and is now seventh.
Boy Van Poppel (Trek Factory Racing) was the first rider our of the start gates for the decisive 38.7km long individual time trial around Burgos and former race leader Joaquin Rodriguez (Katusha) the last.
Bodnar set the benchmark to beat early in the piece and sat in the hot seat until Dumoulin raised the bar for the top three riders to come.
The final outcome of the race remains on a knife-edge with Dumoulin (Giant-Alpecin) sure to come under pressure from Aru (Astana) and the rest of the climbers. While the next two stages would normally be classified as breakaway stages, the complex rolling terrain provides ample opportunity for a surprise ambush - and there's still one major mountain stage to go on Saturday. A Dumoulin victory is far from assured.