Geraint Thomas won Stage 12 of the Tour de France and retained the yellow jersey in a thrilling finish on Thursday in Alpe d'Huez.
Dutchman Steven Kruijswijk led the Tour for most of the day and was over 4 minutes ahead of Thomas and the peloton before the 13.8-kilometer, 8 percent gradient, final climb to Alpe d'Huez, in a virtual lead in the general classification.
Thomas, along with Team Sky teammate Chris Froome, closed the gap during the ascent, and with only 1 kilometer to go, five riders were in contention for the stage as Tom Dumoulin, Romain Bardet and Mikel Landa joined the Team Sky men in the lead.
But it was the yellow jersey-wearer who pulled away to win the iconic Alpe d'Huez stage, delivering another emphatic statement of his general-classification credentials as he extended his lead over Froome to 1 minute, 39 seconds.
"Honestly I'm speechless," said Thomas, who became the first British rider to ever win in Alpe d'Huez.
"I don't know what to say. Not a chance in hell I thought I was going to win today. It's just unbelievable. Can we just go to Paris now?
"Maybe I can keep the yellow jersey for the next few days, but this race is so hard. You never know how the body reacts. But I'm still riding for Froomey. He's a legend, probably the best ever. I'm just going to enjoy this. It's great. I can't believe it. Alpe d'Huez, man. ... Speechless."
In the 175.5-kilometer stage starting in Bourg-Saint-Maurice, Kruijswijk was one of the riders to break away from the peloton along with Julian Alaphilippe, who extended his lead in the king of the mountain standings by winning the first climb of the day at Col de la Madeleine.
Along with several other riders, Alaphilippe dropped off after the second climb of the day at Lacets de Montvernier, leaving Kruijswijk alone at the front of the race with 73 kilometers to go.
Kruijswijk continued to set an impressive pace and was all alone as he reached the top of the penultimate climb at Col de la Croix de Fer.
With Thomas and Froome leading the peloton, the Team Sky riders started to close in on Kruijswijk as they entered the twisting, 21-turn ascent to Alpe d'Huez.
With only 9 kilometers to go, Thomas and Froome had cut the gap to 3 minutes, meaning Kruijswijk was barely ahead in virtual general classification.
After a brave effort, Kruijswijk dropped back with 5 kilometers to go as Thomas, Froome, Dumoulin, Bardet and Landa jostled for the lead.
Froome initially attacked but was quickly caught by Thomas, and in a potentially Tour-defining finish, it was the Welshman who was able to pull away.
In the final of three stages to take place in the Alps, several riders abandoned the Tour after being dropped by the peloton. Dylan Groenewegen, the winner of Stages 7 and 8, Andre Greipel and Fernando Gaviria all quit during Stage 12, joining riders such as Mark Cavendish and Marcel Kittel, who were dropped during Stage 11.
1. Geraint Thomas (GBR) Team Sky 5:18:37
2. Tom Dumoulin (NED) Team Sunweb +2
3. Romain Bardet (FRA) AG2R La Mondiale +3
4. Chris Froome (GBR) Team Sky +4
5. Mikel Landa (ESP) Movistar Team +7
1. Geraint Thomas (GBR) Team Sky 49:24:43
2. Chris Froome (GBR) Team Sky +1:39
3. Tom Dumoulin (NED) Team Sunweb +1:50
4. Vincenzo Nibali (ITA) Bahrain-Merida +2:37
5. Primoz Roglic (SLO) Team LottoNL-Jumbo +2:46