Kuss takes Vuelta stage six as Evenepoel concedes lead
Jumbo-Visma rider Kuss and his teammates enjoyed a fine afternoon, with general classification contenders Jonas Vingegaard and Primoz Roglic putting 32 seconds into Evenepoel.
The Belgian Soudal-QuickStep rider said Thursday he aimed to give away the red jersey on this stage, but he would not have wanted to lose time to his rivals.
French rider Martinez, of team Groupama-FDJ, now leads overall by eight seconds from Kuss, with Evenepoel two minutes and 47 seconds behind in ninth.
"The whole day I felt super super good, I was only thinking about when to go," said Kuss.
"The whole climb I was just enjoying the environment and it's always a special race for me."
Evenepoel's decision, one he also made at the Giro d'Italia, created a frantic start to the stage, with frequent attacks.
UAE Team Emirates rider Jay Vine had to abandon the Vuelta after a crash in the opening section.
Eventually, a huge breakaway group of over 40 cyclists formed, carving out a lead of more than six minutes on the peloton.
For a while, it looked like Evenepoel's plan had spiralled out of hand, with the peloton having to work very hard to reel in the break in the 183.5 kilometres stage between La Vall d'Uixo and the final Javalambre mountain climb.
Ineos, Movistar and Soudal-QuickStep controlled the peloton, collaborating to shave down the gap because of four Jumbo-Visma riders in the break, including stage winner Kuss.
Marc Soler snatched six bonus seconds for the intermediate sprint, aiming to battle Martinez for Evenepoel's red jersey, but the Frenchman crossed the line second, 26 seconds behind Kuss, to claim it.
The break hit the base of the category one final climb, Pico del Buitre - Vulture's Beak - with three minutes 44 seconds' advantage, virtually confirming there would be a new red jersey.
Kuss attacked, passing Movistar's Einer Rubio and sailed through to the finish in style, high-fiving spectators before crossing the line.
In the peloton, Roglic launched an attack, with Vingegaard, Aleksandre Vlasov and Enric Mas following him, while Evenepoel could not respond.
However, the QuickStep rider, isolated, pushed himself and ensured he only lost half a minute to his main Jumbo-Visma rivals.
Stage seven on Friday takes riders 201 flat kilometres from Utiel to Oliva, an easier ride for the general classification contenders and likely to offer a bunch sprint finish.
This is the 78th edition of the race, which ends in Madrid on September 17 after 21 stages and 3,153.8 kilometres.
The early stages of the race have been beset by problems including bad weather and an attempted sabotage plot in the name of Catalan independence which was foiled by Spanish police.