Chris Froome came within a whisker of claiming his first Vuelta a España stage win in four years after the Sky rider dug deep to go clear on the Cumbre del Sol climb in what was the Briton's first real show of strength in the Spanish Grand Tour.
Thanks to his attack, the Sky leader's bid to become the first winner of the Tour and Vuelta in the same year since Bernard Hinault has regained all the momentum it lost on Friday's mountain stage, when Froome suffered and ceded nearly 30 seconds on the other favourites when he was dropped some two kilometres from the line.v
48 hours later, the boot was truly on the other foot as Froome stomped away 300 metres from the line, passing Dumoulin and looking to be en route to his first victory since the Tour this summer.
Dumoulin recovered to pass Froome a little closer to the summit, with the Briton forced to settle for second, two seconds back. But if Froome told reporters after the finish that he was disappointed at losing the victory at the last possible moment, the Sky rider nonetheless has moved back up to eighth overall, 1:18 down on the Dutchman.
"I'm gutted, I thought I had it for a second there," Froome said afterwards. "But Dumoulin's in incredible form, hats off to him, he's a young rider with a bright future ahead of him."
After thanking his team for keeping Sky's "four climbers in perfect position" - himself, Mikel Nieve, Sergio Henao and Nicolas Roche - throughout a fraught, fast stage, Froome disagreed with one reporter who asked him if he had attacked from too far out.
"I don't think so, I gave it everything," he said. "I did try and ride more conservatively at the bottom" - when he was briefly gapped by the rest of the field - "to try and save some energy for an effort at the top if I had the legs."
"[But] more than anything I was happy I was up there and that I didn't lose too much time today."
Sky had a strong stage all round, placing no fewer than four riders in the top thirteen - Froome in second, Nicolas Roche in eighth, Sergio Henao in 11th and Nieve, 13th at 56 seconds.
On top of that Geraint Thomas was present in the day-long breakaway and was only reeled in at the foot of the final climb. Overall Roche is fourth whilst Froome has now moved up to eighth, giving the British team solid options when it comes to the second week of mountain racing.
Froome's next big challenge will come on Wednesday's daunting stage through Andorra, featuring no fewer than six separate ascents and nearly 5,000 vertical metres of climbing. But Froome's performance would seem to confirm Sky's claims that the Briton is building towards a much stronger second half of the race - where rather than mountain skirmishing as up to now, the Vuelta will be decided.