JACA, Spain -- Overall leader Joaquin Rodriguez extended his advantage over Christopher Froome and Alberto Contador by surging ahead on the closing climb to win Thursday's sixth stage of the Spanish Vuelta.
The Spanish cyclist stuck with Froome before coming around the last corner ahead of his Sky rival to secure a 5-second victory under a scorching sun.
Katusha rider Rodriguez needed 4 hours, 15 minutes, 56 seconds to win the 109-mile stage and extend his overall lead on Froome to 10 seconds.
"I went for it today, I didn't think anyone could surprise me," said Rodriguez, who has an overall time of 22:04:32. "Froome didn't think he could shake me, he was struggling. He practically helped me to the finish."
Contador, the 2008 champion, was 36 seconds behind in third. Colombian rider Rigoberto Uran finished in the same time as Contador to sit fourth overall, 42 seconds behind Rodriguez.
Contador, who missed the Tour de France because of a doping ban, became weary at the end.
"I started feeling cramps on the last ascent due to the heat and high temperatures, and I told myself: 'Alberto, go as far as you can.' I think I saved the day all right," Contador said. "It wasn't my best climb, I know that. But the loss was kept to a minimum."
Robert Gesink of the Netherlands is 54 seconds back in fifth, tied with Valverde, the 2009 champion.
The seventh stage Friday caps the first of three weeks of racing, with a 102-mile leg finishing up in Motorland Aragon.