Astana rider Lopez secured the biggest win of his career when he burst clear of a breakaway group.
Astana rider Lopez secured the biggest win of his career when he burst clear of a breakaway group in the closing two kilometres of the challenging 187.5km ride from Lorca to the summit finish in Calar Alto.
"I'm very happy, the rain made the stage difficult, but the team worked very well," said the 23-year-old Lopez, participating in just his second Grand Tour.
"I was familiar with the climb and I preferred to wait to attack a kilometre or a kilometre and a half from the finish."
Froome, hoping to add this to his triumph in this season's Tour de France, crossed in second, 14sec adrift, to retain the overall leader's red jersey and extend his lead to one minute and 19 seconds.
"I'm very happy with the outcomes from today. It was a very selective day for the GC. To finish second, I couldn't ask for much more than that," said Froome.
Italy's Vincenzo Nibali took third, lifting him into second above Colombian Esteban Chaves in the overall standings.
The big loser on the day's ride in rain was Ireland's Nicolas Roche, who started the day 36sec behind Froome but ended it staring at a 4min 45sec deficit, dropping him from third to 11th in the general classification.
Froome is aiming to become only the third man to win the Tour and Vuelta in the same year.
Thursday's 12th stage is a 160km ride from Motril to Antequera featuring a first and second category climb.