Katusha's Daniel Moreno won the fourth stage of the Vuelta a Espana as Sylvain Chavanel (Quick-Step) claimed the overall lead and sprinter Mark Cavendish (HTC-Highroad) abandoned the race.
The 170.2 kilometres stage from Baza saw the first real mountain stage arrive uncharacteristically early in the season's final Grand Tour, complete with a gruelling 2,112 metres summit finish at Sierra Nevada.
A first and third category climb had already strung out the field - and contributed to Cavendish's exit - meaning that a select group of around 50 riders had an early breakaway group well within their sights approaching the final 23km ascent.
The catch came with 7km remaining and it was at that point that Chris Anker Sørensen (Saxo Bank Sungard) chose to attack off the front, with Guillaume Bonnafond (AG2R) the only one of the escape group able to get on his wheel.
Moreno then came out of the pack to bridge the gap and as Bonnafond dropped back it became a two-way battle, with Sørensen and Moreno having a 15 seconds advantage over the rest heading under the flamme rouge.
And it was Moreno, a stage winner at the Vuelta a Burgos earlier in the month, who was much the fresher in the closing stages as he surged past to win by three seconds.
Daniel Martin (Garmin-Cervelo) won the sprint for third, just ahead of Moreno's team-mate Joaquim Rodríguez. That front group, which included Team Sky's Bradley Wiggins, were all credited with the same time, 11 seconds down on the winner.
Chavanel had started to lose touch with that selection 2km from the top but he battled well to limit his losses and was rewarded with the leader's red jersey. He is 43 seconds clear of Moreno on the general classification, with Jakob Fuglsang (Leopard Trek) a further six seconds back in third.
One of the big losers on the day was Igor Antón (Euskaltel) who began the race as one of the big favourites for the overall but lost 1:36 on the stage.
And earlier all eyes had been on Cavendish as he abandoned with around 40km remaining.
The winner of the green jersey at the Tour de France, the HTC-Highroad sprinter was planning to use the Vuelta to help his preparations for the World Championships in Denmark next month.
He had started stage four in 184th position, 16 minutes and 48 seconds adrift, and was again well off the pace when he pulled out - click here for more details.