The Colombian star and reigning champion had been among the frontrunners in the opening two weeks of the race, before cracks started to show on stage 13 to Puy Mary.
But as the race hit the toughest mountains so far on stage 15 to Grand Colombier, Bernal’s armour shattered as he was dropped on the final climb of the day, losing more than seven minutes by the finish.
The 23-year-old is now out of the race for the yellow jersey, as Primož Roglič (Jumbo-Visma) and Tadej Pogačar (UAE Team Emirates) have begun to ride clear at the top of the standings.
Speaking after a hugely disappointing day for Ineos Grenadiers, Bernal said: “I was not going well from the first climb to be honest, I was almost dropped there, I was suffering from the first climb. I told the team I was not good, but then I was trying to fight until the final and give my best.
“It’s difficult to say how I felt, the feeling was that I was empty - I had no power. When the other riders did a big acceleration, I couldn’t go too hard to follow, but then I recovered really quickly, but my body couldn’t react as normal.
“I’m the number one and I tried to give my best, but finally there were riders who were stronger than me."
Ineos had problems throughout the day, which started with a crash for their key support rider Richard Carapaz early in the stage.
Then on the penultimate climb of the day, the Col de la Biche, the British WorldTour team lost most of their domestiques under the pressure being set by Jumbo-Visma, leaving Bernal isolated.
On the final climb of the day, Grand Colombier, Jumbo continued to set a devastating pace on the climb, with Wout van Aert still leading the group of favourites when Bernal began to lose contact, 13km from the summit.
Surrounded by his team-mates, Bernal continued to lose as the GC group went on to fight for the stage.
At the top of the climb Bernal had lost 7-20 on the yellow jersey, dropping down to 10th overall more than eight minutes off the race lead.
He said: “Even if I start the last climb with the other GC riders I felt I would be dropped, I wanted to give my best, not just for me, but for the team and for the respect I have for the race.
“Theres no excuses, I tried to fuel my body in the best way possible, but I don’t know, I didn’t have the legs. The other riders have been stronger than me and we have to accept that.”
Thank you for reading 20 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1