Spain -Spaniard Joaquim Rodriguez claimed the 15th stage of Spain's Vuelta to move within one second of overall leader Fabio Aru on Sunday.
Rodriguez, 36, was strongest on the 12.7km category one climb to the finish of the 175.8km ride from Comillas to Sostres to win from Poland's Rafal Majka and fellow-Spaniard Daniel Moreno.
Aru, who is bidding to go one better than his runners-up spot in this year's Giro d'Italia, was fifth on the day, 15 seconds behind, to hold onto his lead by the slenderest of margins.
Majka's second place was also enough to move him up to third overall, 1min 24sec behind.
It was a tough day for Dutchman Tom Dumoulin, though, as he was dropped on the final climb and falls to fourth overall, one second behind Majka.
"It is a big confidence boost because we have been looking for the stage win and to be involved in the general classification as well is great," Rodriguez told Television Espanola.
"We are in a perfect position, just one second off Aru. Whoever is the strongest will win this Vuelta so being ahead or behind by a second I don't think makes a big difference. The most important thing is that I am feeling very good," added Rodriguez, who has twice finished third in his home Tour in 2010 and 2012.
A nine-man breakaway had led the stage for most of the day, but the peloton never allowed them a lead of more than four minutes to ensure there would be no repeat of Saturday's breakaway victory for Alessandro De Marchi.
Nairo Quintana was the first of the general classification favourites to attempt an attack, but the 2014 Giro d'Italia champion was kept in check by Aru's Astana team.
Rodriguez made his break for the line with a kilometre to go and neither Quintana or Aru could respond to allow the Katusha rider to add a first Vuelta stage victory for two years to his two wins at the Tour de France in July.
Quintana remains three minutes back in ninth overall, 35 seconds behind his Movistar teammate Alejandro Valverde.
"Rodriguez had a great stage, but there are still stages left to achieve things in this Vuelta," said Aru.
Dumoulin, who is one of the big favourites for Wednesday's 38.7km time trial in Burgos, recovered well from being dropped by the peloton to limit the damage as he finished 51 seconds back in 12th.
"I tried to go at my rhythm and not get involved with the real climbers. I am doing better on the mountains, but not like them," said Dumoulin.
"I have to prepare for the time trial with the same calm that I have up until now. If it goes well then it will be great for me and the team, but it is clear everyone wants to win this Vuelta and there can be only one winner."