Chris Froome lost significant time to Vincenzo Nibali as the battle for the red jersey was reignited at the Vuelta a Espana, but Alberto Contador fell short in his pursuit of breakaway stage 17 winner Stefan Denifl.
General classification leader Froome almost doubled his lead with a dominant time trial victory on stage 16 on Tuesday.
However, the Briton - aiming for a Tour de France-Vuelta double - was unable to respond as first Contador and then a group of peloton riders, including Nibali, attacked on the final climb of the 180.5-kilometre trek from Villadiego to Los Machucos. Monumento Vaca Pasiega.
Spaniard Contador, aiming for a stage victory on his last Vuelta appearance, picked off several breakers, but Denifl - who had formed part of the initial breakaway group - finished 28 seconds ahead to secure a maiden stage win at Grand Tour level and secure Aqua Blue Sport a glorious triumph on their major bow.
Nibali (Bahrain-Merida) was more than a minute behind Denifl, but gained 39 seconds on Froome.
The Team Sky leader still owns a lead of one minute and 16 seconds over Nibali, but with four stages still remaining the Italian victory is not as clear cut as it was looking 24 hours ago.