Defending Vuelta a Espana champion Primoz Roglic powered clear of Egan Bernal to win stage 17 and reclaim the leader's red jersey.
Roglic followed a long-range move by Bernal before riding clear 7.5km from the top of the iconic summit finish on Lagos de Covadonga.
The Colombian ended up seventh in a group containing Britain's Adam Yates.
Slovenia's Roglic now leads the general classification by two minutes and 22 seconds from Enric Mas.
"It went well today. I enjoyed it and it was a super nice day for me and the whole team," Roglic said.
"It was a real show, real racing."
The Jumbo Visma rider had previously spent six days in the maillot rojo - but going into the mountainous 186km stage from Unquer, he was 96 seconds behind Odd Christian Eiking in the general classification.
However, the Norwegian had a day to forget. He was dropped as Bernal went on the attack with 61km to go and then crashed in wet conditions on the descent of Collada Llomena to drop down to 11th overall.
The race remains in the Asturian mountains on Thursday with another summit finish on the 162.6km course from Salas to the Alto d'el Gamoniteiru.
Stage 17 results
1. Primoz Roglic (Slo/Jumbo-Visma) 4hrs 34mins 45secs
2. Sepp Kuss (US/Jumbo-Visma) +1mins 35secs
3. Miguel Angel Lopez (Col/Movistar) Same time
4. Adam Yates (GB/Ineos Grenadiers)
5. Jack Haig (Aus/Bahrain Victorious)
6. Enric Mas (Spa/Movistar)
7. Egan Bernal (Col/Ineos Grenadiers
8. Gino Mader (Swi/Bahrain Victorious)
9. Louis Meintjes (SA/Intermarche-Wanty-Gobert) +2mins 29secs
10. Clement Champoussin (Fra/AG2R-Citroen) +2mins 44secs
General classification after stage 17
1. Primoz Roglic (Slo/Jumbo-Visma) 68hrs 42mins 56secs
2. Enric Mas (Spa/Movistar) +2mins 22secs
3. Miguel Angel Lopez (Col/Movistar) +3mins 11secs
4. Jack Haig (Aus/Bahrain Victorious) +3mins 46secs
5. Guillame Martin (Fra/Cofidis) +4mins 16secs
6. Egan Bernal (Col/Ineos Greandiers) +4mins 29secs
7. Adam Yates (GB/Ineos Grenadiers) +4mins 45secs
8. Sepp Kuss (US/Jumbo-Visma) +5mins 04secs
9. Felix Grossschartner (Aut/Bora-Hansgrohe) +6mins 54secs
10. Gino Mader (Swi/Bahrain Victorious) +6mins 58secs.