Team Liquigas-Cannondale's Peter Sagan showed he is the rider to beat in the 2011 Tour of Spain's bunch sprints by picking up his second stage victory earlier today.

Already the winner of stage six into Cordoba in Andalusia following a fast descent, the Liquigas rider was equally unstoppable on the 12th stage's slight rise into the Galician port of Pontevedra.

He finished ahead of Germany's John Degenkolb and Italy's Daniele Bennati to claim his 13th victory of the season, while Britain's Bradley Wiggins retained the overall lead.

The second most prolific winner this season behind Belgian Classics specialist Philippe Gilbert, who has 16, Sagan said he would be willing to sacrifice his chances of a third Vuelta victory for his team.

"I will keep sprinting, but [Liquigas team leader] Vincenzo Nibali has an excellent chance of winning the race outright, so we have to respect that," the 21-year-old told reporters.

"This is my first ever big Tour, and it couldn't be going any better, but from now on my own personal objective is to get to Madrid."

Sagan said the sprint had been chaotic because of the short but punishing drag up into Pontevedra city centre.

"There was a lot of confusion, riders trying to get ahead all over the place," he said.

"I followed [rival Fabian] Cancellara [of Switzerland] and that was a good wheel to follow because he was working Bennati.

"Tomorrow [Friday] we're back into the mountains so we had to make the most of our opportunities."

In the overall standings, Wiggins leads team mate and compatriot Chris Froome by seven seconds for a second day, with Sweden's Fredrik Kessiakoff in third, nine seconds back, and Nibali fourth, at 10 seconds.

Wiggins' main rival Nibali clawed back a second after the bunch shattered on the final slight climb.

"It was a sprint day, but it was still really hard, not flat by any means," Wiggins told Reuters.

"I stayed close to the front which probably isn't where you'd expend the least energy but it's certainly the safest."

After his crash in the Tour de France, where he broke his collarbone when he fell in the first week in the middle of a speeding pack, the Team Sky rider said he was still slightly uncomfortable in bunch sprints.

"I just tried to stay out of trouble, I still get a bit nervous in those sorts of situations," he said.

Looking forward to the next three days in the mountains, Wiggins said he was feeling confident.

"Tomorrow will be tough, but I don't think I'll be in too much difficulty because it [the last climb] is a long way from the finish," he said.

"Everybody knows Sunday will probably decide the Vuelta.

"We're in a good position, I'm just trying not to get too carried away with it all."

The 2011 Vuelta a Espana ends in Madrid on September 11.

Watch video highlights from all stages of the 2011 Vuelta a Espana in our video section.