Ireland's Philip Deignan outsprinted breakaway companion Roman Kreuziger to take victory in stage 18 of the Tour of Spain.
Deignan, of the Cervelo team, and Liquiqas' Kreuziger moved clear from the initial break of 16 riders in the final two kilometres of the hilly, rainswept 165km route from Talavera de la Reina to Avila.
The duo were left to battle it out for stage honours with Deignan proving too strong for his Czech rival.
Dane Jacob Fuglsang took third for Saxo Bank, 16 seconds behind the winner.
"I was really nervous, I really didn't think I could win it," said Deignan, who is the first Irishman to win a Grand Tour stage since Stephen Roche in 1992.
"I've only been in that situation a couple of times in my career.
"I thought Kreuziger would attack on a cobbled section just coming into the town, or sprint past me at the end, but he can't have had the legs."
After several seasons in which Deignan has been troubled by knee injuries and glandular fever, the 26-year-old felt victory provided confirmation his career was back on track.
"I wasn't sure if it was possible for me to do so well, but this win is very important for my self-confidence," he added.
Caisse d'Epargne's Alejandro Valverde retained the overall leader's gold jersey.
A group of four general classification contenders - Valverde, Cadel Evans, David Garcia and Samuel Sanchez - stole a march on the rest of the pack to finish a second clear of the main group, meaning Valverde's lead over second-placed Robert Gesink is now up to 32 seconds heading into the final three days of the race.
Gesink, along with sixth-placed Ezequiel Mosquera had gone to hospital last night for tests after suffering a spill on stage 17, and although both were able to continue, the chances of anyone pipping Spain's Valverde to glory in Madrid on Sunday appear slim.
The Vuelta continues on Friday with a 174km trek from Avila to La Granja.
Stage 18 result:
1 P Deignan (Ireland/Cervelo) 4 hrs 19 mins 14 secs
2 R Kreuziger (Czech Republic/Liquigas) +3 secs
3 J Fuglsang (Denmark/Saxo Bank) +16"
4 M Vazquez (Spain/Contentpolis) +39"
5 I Anton (Spain/Euskaltel) +41"
6 M Cherel (France/Francaise des Jeux) +42"
7 R Taaramae (Estonia/Cofidis ) "
8 R Di Gregorio (France/Francaise des Jeux) "
9 J Hernandez (Spain/Astana) "
10 J Del Nero (Spain/Fuji) same time
1 A Valverde (Spain/Caisse d'Epargne) 78 hrs 56 mins 42 secs
2 R Gesink (Netherlands/Rabobank) +32 secs
3 S Sanchez (Spain/Euskaltel) +1:10"
4 I Basso (Italy/Liquigas) +1:29"
5 C Evans (Australia/Silence-Lotto) +1:51"