Joaquin Rodriguez landed a psychological blow on closest rival Alberto Contador as he won the 12th stage of the Vuelta a Espana to extend his lead.
Rodriguez, who began the day a single second ahead of Contador, was left in a head-to-head with his fellow Spaniard after they broke away from the peloton in the closing stages of the 12th stage.
It was the red jersey holder who pulled away, however, to secure a potentially decisive success and increase his lead to 13 seconds - albeit with with nine stages still remaining.
Ireland's Nicolas Roche finished ninth on the stage and remains in seventh place in the overall standings.
Team Sky's British hopeful Chris Froome saw his bid suffer a setback as he crossed in fifth which, while good enough to keep him in third overall, saw him slip 51secs off the pace.
The riders will enjoy a sedate day in the saddle tomorrow with the relatively flat 173km trip from Santiago de Compostela to Ferrol before three crucial mountain stages.