Slovenian Primoz Roglic powered past reigning champion Remco Evenepoel to win the eighth stage of the Vuelta a Espana after a tough fight on the climb to Xorret del Cati on Saturday.
Roglic's Jumbo Visma teammate Sepp Kuss took the overall leader's red jersey after Lenny Martinez of Groupama-FDJ cracked near the finish of the 165km stage from Denia.
Kuss is the first American to lead a Grand Tour since Chris Horner at LA Vuelta in 2013.
The peloton reeled in four breakaway riders at the start of the brutal final climb and battle commenced amongst the general classification contenders with Jumbo Visma again dominant.
Kuss was the first to attack before Belgium's Evenepoel (Soudal Quick Step) took it on over the summit on the downhill race to the finish line.
Evenepoel was unable to hold off three-time Vuelta winner Roglic in the final sprint to the line but looked strong as he came home in second place with Spain's Juan Ayuso third.
Danish co-favourite Jonas Vingegaard, also of Jumbo Visma, was fifth with Kuss seventh.
With Frenchman Martinez more than a minute behind at the finish, Kuss now leads the standings by 43 seconds from Spain's Marc Soler (UAE Team Emirates) and one minute from Martinez.
Evenepoel, Roglic and Vingegaard are well-placed in sixth, seventh and eighth places, around two and a half minutes behind Kuss but with two weeks of racing still to go.
Anyone assuming Kuss will just revert to his role of supporting more illustrious teammates may have to reconsider as the American again showed great legs.
"You always hope for the best. The guys did a really amazing job, controlling the really strong breakaway. Then we had no option in the end," Giro d'Italia winner Roglic said.
"In the sprint, it's always a bit of a gamble but I had the legs and I could do it. At least three (Jumbo-Visma leaders) now, no? But maybe there's still someone coming!"
More mountains are in store on Sunday with a 184-km route starting in Cartagena.