Chris Froome took another huge step towards Tour de France victory by dropping all of his closest rivals on a mountainous 17th stage won by Russian breakaway rider Ilnur Zakarin.
Froome of Team Sky attacked out of a heavily thinned-down peloton with about 1.5km left to the summit finish at Finhaut-Emosson and crossed the line eight seconds ahead of Adam Yates of Orica-BikeExchange, 28 seconds in front of Movistar’s Nairo Quintana and 40 seconds up on Bauke Mollema of Trek-Segafredo.
The result sees him stretch his lead at the top of the general classification to 2min 27sec over second-placed Mollema and 2min 53sec over third-placed Yates, while Quintana is now 3min 27sec down in fourth.
Having initially been dropped by Froome, the 23-year-old Briton left behind a group containing the likes of Quintana and Astana’s Fabio Aru with a counter-attack inside the final 1km and might have caught Froome and Porte had he not run out of road.
Zakarin who rides for Katusha, meanwhile, formed part of a 14-man breakaway but moved into a lone lead with an attack at the foot of the final climb and hung on to beat Jarlinson Pantano of IAM Cycling into second place by 55 seconds and Tinkoff rider Rafal Majka into third by 1min 26sec.
Stage 17 was the first of four back-to-back days in the Alps and ended with the 13km climb of the Col de la Forclaz and then an super-category final climb to Finhaut-Emosson in Switzerland.
The peloton was thinned down to about 40 riders on the Forclaz in temperatures reaching into the mid-30s and was then cut by half again when Aru’s Astana set a fierce pace on the last ascent.
It looked certain that Aru would launch an attack but he didn’t, and when Dan Martin of Etixx – Quick-Step and Movistar’s Alejandro Valverde both had moves snuffed out by Team Sky, it was left to Porte to blow the group of favourites apart with his acceleration about 2km out.
Froome waited 500m before launching a counter-attack and although Quintana initially followed, he blew him away with a second surge a couple of hundred metres later and swiftly caught up to Porte.
Quintana subsequently formed part of the chase group, but he was left behind again when Yates attacked and drew responses from Aru and Romain Bardet of Ag2r-La Mondiale.
The Tour continues tomorrow with a mountainous 17km individual time trial from Sallanches to Megeve.
Stage 17 result
1 Ilnur Zakarin (Rus) Katusha, 4:36:33
2 Jarlinson Pantano (Col) IAM Cycling, +55sec
3 Rafal Majka (Pol) Tinkoff, +1:26
4 Kristijan Durasek (Cro) Lampre-Merida, +1:32
5 Brice Feillu (Fra) Fortuneo-Vital Concept, +2:33
6 Thomas Voeckler (Fra) Direct Energie, +2:46
7 Domenico Pozzovivo (Ita) Ag2r-La Mondiale, +2:50
8 Stef Clement (Ned) IAM Cycling, +2:57
9 Steve Morabito (Sui) FDJ.fr, +4:38
10 Richie Porte (Aus) BMC Racing, +7:59
11 Chris Froome (GB) Team Sky, same time
12 Adam Yates (GB) Orica-BikeExchange, +8:07
16 Nairo Quintana (Col) Movistar, +8:27
18 Bauke Mollema (Ned) Trek-Segafredo, +8:39
1 Chris Froome (GB) Team Sky, 77:25:10
2 Bauke Mollema (Ned) Trek-Segafredo, +2:27
3 Adam Yates (GB) Orica-BikeExchange, +2:53
4 Nairo Quintana (Col) Movistar, +3:27
5 Romain Bardet (Fra) Ag2r-La Mondiale, +4:15
6 Richie Porte (Aus) BMC Racing, +4:27
7 Alejandro Valverde (Esp) Movistar, +5:19
8 Fabio Aru (Ita) Astana, +5:35
9 Dan Martin (Irl) Etixx – Quick-Step, +5:50
10 Louis Meintjes (RSA) Lampre-Merida, +6:07