Egan Bernal (in white) is poised to become Colombia's first Tour de France champion and the youngest winner since World War II. Photo / Getty Images
It was the day French dreams died, Thibaut Pinot abandoning in tears with an injury to his leg and Julian Alaphilippe cracking on the Col de l'Iseran.
The day Geraint Thomas' challenge for a second Tour de France title ended, superseded by a younger teammate. The day a 22-year-old Colombian, riding in only his second grand tour, soared into yellow.
What a day it was; crazy, chaotic, in keeping with this enthralling race. But what a shame it had to end like this. In controversy.
All hail the 2019 Tour de France, the best edition in a generation. But now one destined, sadly, to be remembered for a freak hailstorm and mudslide 20km from the finish of stage 19, forcing the neutralisation of the stage at the critical moment — and the hugely controversial decision to award general classification times from the top of the penultimate climb.
With Egan Bernal (Team Ineos), second at the start of the day, having attacked towards the summit of the Col de l'Iseran, the highest point in the race at 2770m, and having gained around a minute on a chase group including Thomas, and around two minutes on the maillot jaune Alaphilippe (Deceuninck-Quick Step), he was best placed to profit when race commissaires called a halt to proceedings.
Their decision was understandable. Further down the valley, just after Val d'Isere and before the riders turned back on themselves for the final climb up to Tignes, hailstorms were battering the road.
Snowploughs had been deployed in an attempt to sweep the debris, water and slush off the road in time. When a mudslide then cascaded over the race route at La Daille, the commissaires were left with no choice.
"First and foremost, you've got to think about people's safety," said Ineos team principal Sir Dave Brailsford. "I saw images of the stuff coming down. If the riders had been in there, we're talking a major crisis situation, so they had no choice."
That is unarguable. What was more controversial was the decision to award GC times based on the summit of the Iseran. Quite apart from the fact that there were no official timing controls at the summit, there was the fairness of it. Or lack of it.
Those in the chase group, such as Steven Kruijswijk (Jumbo-Visma) and Emanuel Buchmann (Bora-Hansgrohe) could justifiably claim they were racing to Tignes, not the Col de l'Iseran; that they were riding as a group, working together to chase down Bernal.
Thomas, sitting on their wheels, could claim he was conserving energy ready for the final climb up to Tignes when he might launch his own attack. Alaphilippe, despite being two minutes down over the Iseran, was descending like a dervish again, risking it all. He might well at least have caught up to the Thomas group.
We will never know. For a while, as confusion reigned at the finish in Tignes, the whole stage was in doubt. French TV reported that the stage either had to be restarted, or cancelled altogether, which would have put Alaphilippe back in yellow. Eventually, three hours after the stage was neutralised, the official results came in.
The upshot? Barring catastrophe on the road to Val Thorens overnight, we will see Colombia's first Tour winner crowned in Paris.
Bernal will be very short odds to finish the job after leaping from 1m30s down on Alaphilippe to 48s ahead. The stage, from Albertville to Val Thorens, was meant to be a huge alpine affair; but with a difficult weather forecast and the effects of the landslides still being felt, organisers reduced it from 130km to a considerably shorter 59km.
Speaking before the change, Alaphilippe had already effectively conceded defeat.
"I don't think I can [get yellow back]," he said. "It was a dream to have worn it so long. I pushed myself every day and even [yesterday] on the last climb and on the descent ... until I ended up in the car. I want to thank all my supporters. I don't have regrets."
No one else looks capable of taking the race to Bernal. Thomas is the only one who seemed like he could. But he was 1m 16s behind in third and will not attack his team-mate.
Kruijswijk and Buchmann, at 1m28s and 1m55s respectively, do not look like they have the legs.
Kiwi George Bennett, who suffered two crashes on stage 18, was 20th overall, 44m 27s off the lead.
Bernal deserves it. He has raced brilliantly and is a wonderful story. If he holds on, not only will he be Colombia's first winner, he will be the youngest Tour winner since World War II. But what a shame it had to be decided like this.
Then again, this race has thrown up so many surprises, so much drama, perhaps it was appropriate.
On any other day, the sight of Pinot climbing into his team car in floods of tears thanks to a muscular injury picked up this week would have been the biggest story of the race.
Two hours later, it had almost been forgotten on one of the craziest days in Tour history. Chris Froome running up Mont Ventoux a few years ago was extraordinary. Yesterday's hail-battered, mudslide-affected stage was on another level.
It was a week that began with Peter Sagan claiming it would be "suicide" to keep sending the peloton out in 40C heat. Now the race has been decided by hail, ice and landslides.