Primoz Roglic burst away to win a fearsome stage 17 of the Tour de France and Chris Froome extended his lead to 27 seconds on a gruelling day on which Marcel Kittel was a notable casualty.
Roglic made his move six kilometres from the top of the Col du Galibier - the highest summit of the 2017 Tour - and there was no catching the LottoNL-Jumbo rider, who won by a minute and 13 seconds.
The 27-year-old former ski jumper is the first Slovenian to take a stage win in the race after breaking away from the likes of Serge Pauwels and Alberto Contador on the first day in the Alps.
Pauwels had gone out on his own, but was reeled in by Roglic as Contador dropped back after making a long-range attack on the 183km stage from La Mure to Serre-Chevalier on Wednesday - which was watched by President Emmanuel Macron.
Froome reacted to attacks from Romain Bardet and Dan Martin on the brutal 17.7km climb of the iconic Galibier - with a gradient of 6.9 per cent - and the defending champion finished third to increase his advantage by nine seconds.
Fabio Aru was the big loser of the day, slipping from second to fourth in the general classification standings, 53 seconds adrift of Froome with four stages remaining after his GC rivals gave him the slip late in the day.
Rigoberto Uran was second, marginally in front of Froome, so both he and Bardet - who crossed the line fourth - have 27 seconds to make up on Froome ahead of another day in the mountains, which could be decisive.
Points leader Kittel continued with a new bike after waiting for over two minutes at the side of the road following an early crash, but later withdrew from the race after damaging his shoulder and knee, so Michael Matthews takes the green jersey.
GOOD DAY / BAD DAY
Roglic showed incredible stamina to pull off what he described as a "crazy" win on another eventful day, while Froome's GC rivals were unable to shake him off after Team Sky provided great support to the yellow jersey holder and Aru had a day to forget in the mountains.
Kittel won five stages on this year's Tour, but his green jersey was left ripped and bloodied and the German also had a badly cut knee after he was among several riders to go down after only 20km of racing. He had a change of bike and cleat before being treated by a medic, but had to admit defeat.
1. Chris Froome (Sky) 73:27:26
2. Rigoberto Uran (Cannondale) + 0.27s
3. Romain Bardet (AG2R La Mondiale) +0.27s
1. Michael Matthews (Sunweb) 364 points
2. Andre Greipel (Lotto Soudal) 204 points
3. Kristoff Alexander (Katusha Alpecin) 158 points
KING OF THE MOUNTAINS
1. Warren Barguil (Sunweb) 129 points
2. Primoz Roglic (Lotto NL-Jumbo) 80 points
3. Thomas De Gendt (Lotto Soudal) 61 points
Froome will be braced for more attacks from his rivals on Thursday, when the riders tackle a 179.5km route from Briancon to Izoard in what is the final mountain stage.
They will have to leave something in the tank for a finish which is as high as 2,360 metres above sea level after the race returns to the Col du Vars following a 17-year absence.