Fernandez in red as Geniez holds on for stage 3 win in the Vuelta

Fernandez, the Movistar team-mate of Alejandro Valverde and Nairo Quintana, raised his arms aloft and punched the air as he crossed the line apparently believing he had won the 176.4-kilometre stage from Marin in the province of Galicia.

But a delighted Geniez had moments earlier tamed the 30% maximum ramps of the short but sharp final climb, the 28-year-old FDJ rider picking up the second Vuelta stage win of his career and securing the polka dot jersey in the process.

Fernandez’s celebrations were not totally in vain, however: the 25-year-old Vuelta debutant moved into the race lead at the expense of Michal Kwiatkowski (Team Sky) after the Pole conceded more than six minutes in the race's first summit finish.

Fernandez leads compatriot and team-mate Valverde by seven seconds after the Spanish veteran took third place on the stage just ahead of rivals Chris Froome (Team Sky) and Estaban Chaves (Orica-BikeExchange).

Froome sits comfortably in third place in the general classification four seconds further back with Chaves in fourth and level on time with fellow Colombian Quintana, 17 seconds behind Fernandez.

“I’m very happy. It’s been a very difficult season with my crash in Italy. I’ve been working very hard and this is a big moment for me,” said Geniez, who was sidelined for two months with a broken wrist after withdrawing from May’s Giro d’Italia in the fourth stage.

Geniez was part of a seven-man break – featuring Pieter Serry (Etixx-QuickStep), Rudiger Selig (Bora-Argon 18), Gatis Smukulis (Katusha), Simon Pellaud (IAM Cycling), Jerome Cousin (Cofidis) and David Arroyo (Caja Rural-Seguros RGA) – which built up a maximum lead of almost seven minutes under the sun of north-west Spain before splintering in the fierce finale.

“We knew we had a chance because it was a great group and the peloton seemed to have slowed down,” said Geniez, who attacked on the final climb alongside Serry after the pair had earlier reeled in lone leader Pellaud.

Pellaud, the 23-year-old Swiss rider whose team is set to fold at the end of the season, put himself in the shop window after breaking away on the first of three categorised climbs. He crested the summit of the Alto de Lestaio with 60km remaining with a lead of over a minute over his fellow escapees but was caught – and passed – by Geniez and Serry on the Alto de Paxareiras with 22km to go.

Pellaud managed to fight back on although his dreams of a polka dot jersey were in tatters after Geniez had taken maximum points over the decisive Cat.2 climb. And inevitably it was the Swiss rookie who was first to falter on the final climb – deemed one of the hardest in Spain.

“It felt like Alpe d’Huez towards the end – everyone was yelling, the crowds were huge and it was difficult to focus. We don’t have any climbs like this in France,” said Geniez, who recently signed a contract with French team Ag2R-La Mondiale for the next two seasons.

The decisive 1.8km climb – which boasts an average gradient of almost 14% – was also enough to spell the end for Serry, who was caught by the Movistar-led pack in the final kilometre. But Geniez held on for a morale-boosting victory after a tricky season both in and out of the saddle.

The steep gradient – which came after two other categorised climbs in the final third of a testing stage – wreaked havoc on the peloton as numerous big-name riders shipped large swathes of time.

Froome was an early casualty but the British triple Tour de France champion showed his class by fighting back to finish with – or ahead of – his big rivals.

The same cannot be said for Dutchman Steven Kruijswijk (LottoNL-Jumbo), who finished two minutes back, while both American Tejay Van Garderen (BMC) and Frenchman Pierre Rolland (Cannondale-Drapac) came home a further six minutes off the pace.

Spain's Alberto Contador (Tinkoff) also stuttered, the triple Vuelta champion recovering for ninth place on the stage but conceding another 28 seconds to the likes of Froome, Valverde and Chaves.

Meanwhile, Miguel Angel Lopez of Astana – winner of June’s Tour de Suisse – crashed heavily ahead of the final climb to continue his disastrous start to his maiden Grand Tour. Having dropped a chain in the opening team time trial, the fancied Colombian youngster came home a bloodied mess more than 10 minutes down on winner Geniez.

There was also heartbreak for Frenchman Warren Barguil of Giant-Alpecin, who was forced out of the race with sinus problems.

The Vuelta continues on Tuesday with the undulating stage four – a 163.5-kilometre ride from Betanzos to San Andres de Teixido – which features two early Cat.3 climbs ahead of another uphill finishe, a two-tiered Cat.2 climb which should drive a further wedge between the race favourites and pretenders.