The early breakaway was victorious on the top of the steep slopes of Mirador de Ezaro but only Alexandre Geniez proved strong enough to capitalise on the attack's advantage to take the win at the summit.
The FDJ rider took the win 21 seconds ahead of Ruben Fernandez who got the all-clear from his team leaders to attack from the peloton and take the red leader's jersey.
Both celebrated as they crossed the line but for once Fernandez's salute wasn't in error, he was simply acknowledging the momentous occasion of donning the red jersey for the race lead in his home Grand Tour.
After the stage Geniez spoke to the media present about his comeback from injury at the Giro d'Italia, where he was supposed to be the team leader for the overall.
"I'm very happy," said Geniez. "It's been a very difficult season with my crash in Italy. I've been working a lot and now I'm extremely happy. It's a big moment for me. It was close in the end but I got it.
"The beginning of the season didn't go too well. I was very motivated for the Giro and I crashed in the third stage, there was nothing I could do."
"One month later, a wrist fracture was discovered and I was plastered for a month. I returned to the bike only at the start of July. I did everything to come back in shape and I was very motivated for the end of the season.
"I'm delighted, it's fulfilling to win this stage. It was the goal on this Vuelta."
As it happened
Gatis Smukulis and Simon Pellaud (both IAM Cycling), Jerome Cousin (Cofidis) and David Arroyo (Caja Rural) attacked just after another breakaway had been brought back into the fold by the peloton. Alexandre Geniez (FDJ), Pieter Serry (Etixx - Quick Step) and Rudiger Selig (Bora-Argon18) soon joined them to bring their number to seven in total and the bunch were seemingly happy with the break's composition and allowed them to take some time.
Temperatures of up to 33 degrees Celsius assaulted the riders as they attempted to tackle the tough stage, fortunately most of the route went along the coast giving some semblance of a cool breeze for the riders to enjoy.
The break was only given just over five minutes headstart, with most of the riders close on GC this early in the race.
The opening half of the stage was mostly flat, but the back part contained a few categorised climbs which saw Geniez emerge as the best on the climbs to secure the lead in the King of the Mountains classification.
Simon Pellaud tried to attack after one of the ascents and built his advantage to over a minute on his former companions but there was too much flat for one rider to go against six and he was caught on the penultimate climb with 22 kilometres to go.
Geniez and Serry would go on to battle it for the maximum points with Geniez edging out the Etixx-QuckStep rider by the narrowest of margins on the line.
Behind, the peloton finally began setting up their own chase and cut the gap to three minutes thirty seconds by the top of the ascent. the upping of the temp for Tejay van Garderen (BMC) and he lost touch on the Paxareiras, ending up finishing just under eight minutes behind on the stage.
By this point it was clear that it would take a coordinated chase from the peloton to bring back the attackers with Pellaud, Geniez and Serry all working well together up front.
Astana's leader and Tour de Suisse winner, Miguel Angel Lopez, suffered a heavily fall in the bunch on a straight stretch of road.
The Colombian came down hard and took some time to get back up and ended up losing over 12 minutes on the day but his team has confirmed that he will at least start tomorrow's stage.
At the start of the day, most wouldn't have given a breakaway a chance at taking victory with plenty of reason to chase from within the peloton.
At the base of the final climb the three had a lead of two minutes over the main bunch but with the steep ascent it was only Geniez who was able to maintain the push for the stage win, quickly leaving behind his former companions to press on for the victory.
Sky went into the base of the climb with the numbers and race leader Kwiatkowski on the front but were nowhere to be seen when the climb got tough as Movistar took up the pace setting, splitting the group to pieces.
Alberto Contador (Tinkoff) and Steven Kruijswijk (Lotto NL-Jumbo) were the most notable losers from the pace-setting efforts but plenty of other big names struggled on the first major test of the race.
Chris Froome was initially dropped as well but turned out to have been riding conservatively as he powered through a tiring field.
Ruben Fernandez had done a lot of work on the front to drop the majority of the bunch and was given the all clear from his team to attack and take the leader's jersey, which he duly did, as well as a second-placed stage finish.
Valverde jumped clear to claim third on the stage and 2nd overall, with Froome and Chaves (Orica-BikeExchange) finishing on the same time for very solid starts to their Vuelta campaigns.
Quintana was six seconds further back and that quartet of riders have set themselves up as the early pace-setters in the general classification with the only other serious contender within a minute of them on overall being the veteran Samuel Sanchez (BMC)
Pre-race favourite Alberto Contador didn't have his normal punch and came into the finish in ninth, conceding 28 seconds to Valverde, Froome and Chaves and now sits a minute and 31 seconds down on the race lead.
After the stage Ruben Fernandez was ecstatic with his chance to wear red. The former Tour d'Avenir winner has shown a lot of promise since his step up to the World Tour, without that real breakthrough result but had the chance to show his best here.
"I couldn't expect this at all," said Fernandez. "I knew I was coming in good form to this Vuelta, as I had finished sixth overall in both Pologne and Burgos. Plus, my goal here was working for Nairo and Alejandro."
"However, I was told in the finale to ride by myself... and here we are, wearing red and the leader's jersey in my second Grand Tour."
“It hadn't really come through my mind to attack: I was just setting the pace in case Nairo could attack, I was trying to make things harder for the rest.
"In the end, they told me to ride on my own, and I could open that gap. I celebrated out of pure joy, because of the GC lead; by the earpiece I was told I would sit 1st overall after the stage... I couldn't be happier."
Fernandez wasn't getting ahead of himself however and reiterated that the team's focus was very much still on their leaders Valverde and Quintana.
”My goal remains the same: we can't forget for a second about helping out our team leaders, which is the main objective, yet I'll surely defend this jersey with all I've got."
The next stage is the 163.5 kilometre route from Betanzos to San Andre de Teixido, where there will be a longer climb to the summit finish, albeit not as steep as the Mirador de Ezaro.