Chris Horner reclaimed the leader's red jersey at the Vuelta a Espana after winning stage 10 on Monday with an impressive late charge on the final climb in Granada.
The American, who also led the Vuelta after winning stage three, broke away from a talent-packed group that included Vincenzo Nibali, Ivan Basso and Joaquin Rodriguez with around five kilometres to go and none of his rivals could reel him back in.
Horner (RadioShack-Leopard) finished the 168km ride from Torredelcampo to Alto Hazallanas - the first mountain stage of this year's Vuelta - in a time of four hours, 30 minutes and 22 seconds.
Italian Nibali, the 2010 Vuelta winner and 2013 Giro d'Italia champion, tried to chase down Horner but he could only finish 48 seconds back in second spot, with Valderde third a further 14 seconds adrift.
Basso, Rodriguez and Thibaut Pinot completed the top six places, all three with the same time as Valverde.
Ireland's Nicolas Roche crossed the line in seventh, one minute and 10 seconds behind Horner,
Spaniard Daniel Moreno, who took the red jersey with his victory on Sunday, finished 12th, two minutes and 21 seconds adrift of Horner, and that saw him lose first place in the general classifications to the 41-year-old American.
Horner now boasts a 43-second lead over nearest challenger Nibali (Astana), with Roche in third spot 10 seconds back.
Spanish trio Valverde, Rodriguez and Moreno occupy the next three spots.
Tuesday is a rest day.