Tom Dumoulin edged closer to a maiden grand tour title when he smashed the opposition in the 17th stage, a 38.7-km time trial that was fatal to local favourite Joaquim Rodriguez.
Dumoulin (Giant-Alpecin), who limited his losses in the brutal mountain stages, lived up to expectations in the solo effort against the clocking, covering the course in and around Burgos in 46 minutes 1 seconds to claim the overall lead.
He leads Fabio Aru (Astana) by only three seconds, however, after the Italian rider took 10th place.
Rodriguez (Katusha), who started the day with the red jersey 1:51 ahead of Dumoulin, finished a distant 30th, 3:06 off the pace.
He now sits in third place overall 1:15 behind Dumoulin, who beat Maciej Bodnar (Tinkoff-Saxo) by 1:04 and Alejandro Valverde (Movistar) by 1:08.
Bodnar, one of the early starters, set the first time of reference when he clocked 47:05 after a headwind picked up.
He was only to be beaten by Dumoulin.
Cheered on by the crowd, Purito had already lost over a minute to the Dutchman at the first time split (km 13.5), losing all hope early on while Aru rode himself to the ground but failed to get the red jersey back for three seconds.
Valverde produced a fine performance, finishing only four second adrift of Bodnar to move up to sixth overall behind his team mate Mairo Quintana.
Rafal Majka (Tinkoff-Saxo) dropped to fourth overall after finishing in 17th place on the day.
Dumoulin will be on his toes in tomorrow's 18th stage, a 204-km ride from Roa to Riaza featuring a category-one climb 13 kilometres from the finish.
