Annemiek van Vleuten (Movistar) ignited the Queen Stage with the first surge over the Col d'Aspin, drawing out her main rival Demi Vollering (SD Worx), but as the race progressed, she struggled to keep pace and was eventually distanced and then defeated on the summit of the Col du Tourmalet.
Vollering reached the finish line of the iconic ascent with a commanding stage 7 victory and moved into the yellow jersey, while Van Vleuten finished third behind Kasia Niewiadoma (Canyon-SRAM).
The reigning world champion is now third overall at 2:28 behind Vollering, all but ending her hopes of winning a second consecutive title at the Tour de France Femmes.
"For me, the goal on the Col d'Aspin was not to attack and to drop everyone there. It was more to do an effort, and maybe in the end, it was not so smart ... for my shape today on the Col d'Aspin, but you never know," Van Vleuten said after crossing the finish line at the top of the Tourmalet.
"I always like to race with my heart, and you always need to focus on your strengths, and I used my capacity and endurance. It's my way."
Van Vleuten came into the stage in third overall at 55 seconds behind overnight leader Lotte Kopecky (SD Worx) and 12 seconds ahead of Vollering.
After a remarkable season where had won the overall titles at La Vuelta Femenina and the Giro d'Italia Donne, her aim was to defend her title at the Tour de France Femmes with the Col du Tourmalet her best opportunity to gain time on her rivals.
Van Vleuten's searing attack over the Col d'Aspin drew out Vollering and Newiadoma, but on the descent, Niewiadoma opened a gap and rode alone into the base of the Tourmalet.
Van Vleuten and Vollering appeared to play a game of poker out on the roads, neither making the effort to chase Niewiadoma and after an exchange of words, the pair were caught by the next selection that included Kopecky and Marlen Reusser, Ashleigh Moolman-Pasio (AG Insurance-Soudal-QuickStep), and Juliette Labous (Team dsm-firmenich).
"She didn't want to ride. So, I said, 'If you don't ride, then I also don't ride'. She also had a point that she had two teammates behind her, so we waited for it," Van Vleuten said.
"It was not so much about our cooperation. Today was about the Col d'Aspin and Tourmalet, and Demi Vollering was better."
Vollering jumped from the select chase group and immediately opened a gap. She caught and passed Niewiadoma with five kilometres to go on the foggy upper slopes of the hors categorie climb and went on to take the third win for SD Worx and the yellow jersey at the Tour de France Femmes.
Van Vleuten said she struggled to stay with the group, particularly as Labous set a quick pace and she crossed the line in third place 2:34 behind Vollering.
"Of course, I am disappointed, but I can accept it. I didn't do anything wrong. I had the best possible preparation, so I'm happy that I went for it on the Col d'Aspin. I raced for it like I always do; go hard and focus on your strength. I was confident today that I could win," Van Vleuten said.
"In the end, I felt a little bit, on the Tourmalet, that I was... when I looked to the others, and [Juliette] Labous was setting a high pace, I thought back to the Giro, I was better there. I could see in my performance that I didn't have the best day."
The Tour de France Femmes continues with the 22.6km time trial in Pau. Van Vleuten is a two-time world champion and Olympic champion in the discipline and will likely aim for a stage win, while the yellow jersey is now out of her reach.
"I will see. I came here to win the Tour de France and not to get second, third or fourth. To be honest, it's beautiful, and after winning it last year, you only want to win. It's obvious that Demi Vollering was on another level."