Chris Froome extends lead as Ilnur Zakarin wins stage 17

Team Sky’s defending champion Froome finished alongside former team-mate Richie Porte (BMC) almost eight minutes down Katusha’s Zakarin – but ahead of his closest rivals for the yellow jersey at the conclusion of a sweltering 184.5-kilometre stage from Bern.

Froome’s principal contender, the Dutchman Bauke Mollema (Trek-Segafredo), was distanced from the main pack two kilometres from the finish and now trails Froome by 2:27 in the general classification. British youngster Adam Yates (Orica-BikeExchange) fought back to finish just a handful of seconds behind Froome to retain his third place on GC, 2:53 down on the seemingly untouchable race leader.

But Nairo Quintana’s nightmare Tour continued after the Colombian climber from Movistar was distanced by Yates and the other GC pretenders in the final kilometre. Quintana – tipped by many before the Tour to end Froome’s dominance in the world’s biggest bike race – conceded 28 seconds to the Briton and now trails the double champion by 3:27 in fourth place with four stages remaining.

Zakarin’s maiden Tour scalp came after the Russian dropped fellow escapees Jarlinson Pantano (IAM Cycling) and Rafal Majka (Tinkoff) five kilometres from the summit of the fourth and final climb of the day. The 26-year-old Russian barely had the strength to zip up his jersey in the closing metres before celebrating with a simple punch of the air after more than four-and-a-half hours in the saddle.

Colombia’s Pantano, who outsprinted Poland’s Majka to win Sunday’s stage 15 in Culoz, crossed the line 55 seconds down while third-place Majka extended his grip on the polka dot jersey by leading the breakaway over each of the three previous summits in pole position.

Croatia’s Kristijan Durasek (Lampre-Merida) was fourth while Frenchman Brice Feillu (Fortuneo-Vital Concept) completed the top five as the host nation’s search for an elusive stage win continued.

Thomas Voeckler (Direct-Energie), Domenico Pozzovivo (Ag2R-La Mondiale), Stef Clement (IAM Cycling) and Steve Morabito (FDJ) all crossed the line in dribs and drabs from the initial break before Porte took 10th place, 7:59 in arrears, with Froome on his back wheel.

Break: With the peloton swallowing up almost 52 kilometres in the opening hour of racing it was no surprise that it took a long time for any break to stick under the sweltering Swiss sun.

Numerous riders had tried their luck and failed before Rafal Majka (Tinkoff) broke clear in the hunt for king of the mountain points on the first climb of the day, the Cat.3 Cote de Saanenmoser, after the best part of 70 kilometres.

Joining the polka dot jersey were Majka’s Tinkoff team-mate Peter Sagan, Tanel Kangert (Astana), Stef Clement and Jarlinson Pantano (IAM), Kristjian Durasek (Lampre-Merida), Tony Gallopin (Lotto-Soudal), Domenico Pozzovivo (AG2R), Steve Morabito (FDJ), Ilnur Zakarin (Katusha) and Brice Feillu (Fortuneo-Vital Concept).

A group of eight chasers quickly formed featuring Alexey Lutsenko (Astana), Greg Van Avermaet (BMC), Serge Pauwels (Dimension Data), Alberto Losada (Katusha), Rui Costa (Lampre-Merida), Thomas Voeckler (Direct Energie), Julian Alaphilippe (Etixx-QuickStep) and Ruben Plaza (Orica-BikeExchange).

On the second climb of the day, the Cat.3 Col des Mosses, the chase group split with Plaza and Costa dropping off the back and Van Avermaet, Voeckler and Lutsenko riding off the front.

Majka took another two points going over the second summit in pole position before the three chasers joined the leading group to create a select 14-man group that boasted seven previous Tour stage winners in Pantano, Gallopin, Feillu, Van Avermaet, Voeckler, Sagan and Majka.

With the gap back to the peloton now above 13 minutes, Sagan took maximum points at the intermediate sprint at Martigny to continue his utter domination in the green jersey competition he now leads by almost 200 points over Germany’s Marcel Kittel of Etixx-QuickStep – the Slovakian world champion’s closest rival following the rest day withdrawal of Britain’s Mark Cavendish (Dimension Data).

Turning point: The race exploded on the Cat.1 Col de la Forclaz when Gallopin and Lutsenko rode clear of the break while Sagan, his work for the day done, rode off the back.

Back with the peloton, it was the Astana team of Fabio Aru who came to the fore with 2014 champion Vincenzo Nibali and Italians Diego Rosa and Paolo Tiralongo pulling on the front ahead of Chris Froome’s well-oiled Sky army. The remaining three chasers – Alaphilippe, Losada and Pauwels – were duly caught and the scene was set for the final fireworks.

Back on the front the two leaders were reeled in before the summit as Majka took maximum points before being joined on the descent by Pantano – the two riders reacquainting themselves to one another following their joint exploits on Sunday.

Finale: Zakarin attacked his fellow escapees at the start of the final climb of Finhaut-Emosson, the rangy Russian riding off in pursuit of Majka and Pantano who he caught and duly dropped inside the final seven kilometres.

Pantano summoned the strength to fight back on but his time alongside Zakarin was short-lived as the Katusha all-rounder – a stage winner in last year’s Giro d’Italia – made his decisive move with an unseated surge.

But for a few wobbles while trying to zip up his jersey before the finish, Zakarin never looked out of control as he rode to a maiden stage win in his debut Tour.

Some eight minutes further down the road the battle for the maillot jaune intensified when Alejandro Valverde (Movistar), Dan Martin (Etixx-QuickStep) and Aru all attacked in quick succession.

Sky duo Wout Poels and Mikel Nieve managed to neutralise all threats before former Sky rider Porte surged clear with two kilometres remaining. Froome was the only rider who could react, while Nairo Quintana’s miserable day continued when an acceleration by Adam Yates (Orica-BikeExchange) saw him distanced from even the chasing group.

With the focus on his native Russia for all the wrong reasons, Zakarin reminded the cycling world of his talent with a gutsy win that may make up for his likely absence from the Rio Olympics.

“I did my best today. I’m very happy now. Thank you to my team-mates for your super support. This win for me is no surprise,” said the man of few words.

Pantano proved his class once again while Majka – although he missed out on another chance to win a fourth stage on the Tour – edged closer to securing the polka dot jersey in Paris. He now has 173 points – some 83 more than his closest opponent, Thomas De Gendt (Lotto Soudal).

Froome likewise closed in on his third Tour victory but the impressive Porte proved that he could still make the podium by rising to sixth place, 4:27 in arrears.

Quintana’s chances of winning a maiden Tour have all but evaporated after the Colombian struggled to make an uphill impression once again. Quintana not only loses further ground to Froome but moves further behind Yates, whose dreams of a podium finish in Paris are very much alive after another battling performance.

If Quintana’s woe was not enough for Movistar, their Spanish veteran Valverde dropped out of the top five and into seventh after losing time on the final climb following his attempts to pave the way for an attack by his team-mate.

Meanwhile, Porte's path to the podium opened up after his BMC team-mate and co-leader Tejay Van Garderen plummeted out of the top ten after finishing around 18 minutes behind the yellow jersey contenders.

And finally, Spaniard Gorka Izaguirre (Movistar) withdrew from the race after breaking his collarbone in a crash in the neutral zone. Slovenia's Borut Bozic (Cofidis) also hit the deck in the same incident and later withdrew after crashing for a second time alongside New Zealand's Shane Archbold (Bora-Argon18) on the descent of the Col des Mosses.

Back on French soil this mountain time trial tussle could drive a further wedge between the favourites. Two climbs separated by a false flat feature in a stage that finishes in the plush ski resort of Megève, where Chris Boardman won the 1996 Dauphiné prologue and where Cary Grant and Audrey Hepburn first lock eyes in the movie Charade.

The steeper Côte de Domancy (2.5km at 9.4%), where Bernard Hinault powered clear en route to world championship glory in 1980, precedes the gentler Côte de Chozeaux, which flattens twice ahead of a drop to the finish. The question is, will the top rouleurs opt for time trial bikes over regular road machines?