Vuelta victory in sight for Contador

The 29 year old seemed to choke back tears after winning the mountainous 187km Stage 17 from Santander to Fuente De, and giving himself a commanding general classification lead.

He charged over the line six seconds ahead of Movistar's Alejandro Valverde. Sergio Henao (Sky) came in third.

"I wasn’t on one of my best days, but my will to succeed was enormous," said Contador. "Second place isn’t bad but you always have to try and win, even though many people thought it was out of reach for me.

"My attack with 50km to go was of an absolute madness. I told my three team-mates via radio to go 'full gas', and nothing more because sometimes the radios are pirated by other teams. And I’ve climbed with the same conviction I had up to l’Alpe d’Huez in the 2011 Tour de France.

"I am not in my best moment but I had a really strong desire to win. Second place is fine but I was always going to try to win.

"I think we took a huge step forward. I want to dedicate this victory to everyone who has supported me during all this time, my family, my wife, my friends and all the fans."

Describing it as one of his "most emotional wins", Contador said it was an important day because few people were betting him taking the overall leadership of the Vuelta.

"Of course, we still have not won, we have to go in small steps."

The 21-stage race wraps up on Monday (AEST) in Madrid.

Contador had started the mountainous stage through northern Spain 28 seconds behind Joaquim "Purito" Rodriguez (Katusha) in the overall standings for the tour.

But the strong performance catapulted him into first place with a commanding lead in the Vuelta's general ranking, one minute and 52 seconds ahead of Valverde.

Rodriguez's hopes of claiming his first Grand Tour win at the age of 33 look like they are over as he slumped to third place overall, two minutes and 28 seconds behind Contador.

The Katusha rider had entertained great hopes of making up for his heartbreak in this year's Giro d'Italia when he led going into the final stage only to finish second overall after Ryder Hesjedal (Garmin-Sharp) overhauled his advantage in the time trial.

"It is a sad day because I have probably lost the Vuelta. It was a very tough stage. When I saw him coming up on me, I thought, 'This guy wants to break me before the summit'. I had no idea of the disaster he was preparing," Rodriguez said.

With 50km to go in the stage, Contador began to push forward while on a second category climb to Collado de la Hoz, trying to catch up with an 18-man breakaway group while leaving Rodriguez and Valverde in the peloton.

Tactically Contador's Saxo Bank-Tinkoff Bank team had played the stage brilliantly. The break, which had a one minute and 41 seconds lead on the peloton at the 130km mark, included three of Contador's team-mates, Bruno Pires, Sergio Paulinho and Jesus Hernandez, plus long-time friend Paolo Tiralongo of Astana.

Contador passed the summit of Collado La Hoz a 16-second advantage over Rodriguez and Valverde, 55 seconds over Christopher Froome (Sky) and Robert Gesink (Rabobank) who were obviously struggling.

Once in the leading group, Contador was aided by team-mate Paulinho and Tiralongo, who helped him open the gap with the chasing peloton.

Some 15km from the finishing line, Contador already had a lead of more than two minutes over Rodriguez.

On the final climb, Valverde attacked, leaving behind Rodriguez and his shattered Vuelta dream.

“When Contador attacked in the Collado La Hoz, I held Purito’s (Rodriguez) wheel," said Valverde. "We were doing a different race. Mine consisted in distancing (Christopher) Froome. I had to play my cards. I feel sorry for Purito but that’s racing. I’ve ridden the finale flat out. This is one more step towards the podium in Madrid but it’s been a very hard day on the bike.”

In the final three kilometres, five riders including Valverde and Sergio Luis Henao (Sky) picked up the pace to try to rein in Contador. But the 2008 Vuelta champion held them off and now has a lead that will make him tough to dislodge.

"I’ve attacked instinctively. I believe this day of racing has shocked a few," said Contador. "Truly, I’ve ridden a bit like a kamikaze. But I had to try.

"I felt something like an angel and a devil on my shoulders. One was telling me, 'Attack', the other one said, 'Don’t attack'. I followed the right advice. I was scared to lose my advantage in the last 15 kilometres because I hadn’t eaten a lot. I was afraid that other riders could catch me."

On Thursday the riders face a 204.5km mostly flat Stage 18 from Aguilar de Campoo to Valladolid.

Stage 17: 187.3km, Santander to Fuente De
1 Alberto Contador (ESP) Saxo Bank-Tinkoff Bank 4hr 29min 20sec
2 Alejandro Valverde (ESP) Movistar 0:00:06
3 Sergio Luis Henao (COL) Sky
4 Gorka Verdugo (ESP) Euskaltel-Euskadi
5 Rinaldo Nocentini (ITA) AG2R-La Mondiale 0:00:19
6 Jan Bakelants (BEL) Radioshack-Nissan 0:00:55
7 Benat Intxausti (ESP) Movistar 0:01:13
8 Alexandre Geniez (FRA) Argos-Shimano 0:01:40
9 Paolo Tiralongo (ITA) Astana 0:02:13
10 Joaquim Rodriguez (ESP) Katusha 0:02:38

General classification
1 Alberto Contador (ESP) Saxo Bank-Tinkoff Bank 68hr 07min 54sec
2 Alejandro Valverde (ESP) Movistar 0:01:52
3 Joaquim Rodriguez (ESP) Katusha 0:02:28
4 Christopher Froome (GBR) Sky 0:09:40
5 Daniel Moreno (ESP) Katusha 0:11:36
6 Robert Gesink (NED) Rabobank 0:12:06
7 Laurens Ten Dam (NED) Rabobank 0:12:55
8 Andrew Talansky (USA) Garmin-Sharp 0:13:06
9 Igor Anton (ESP) Euskaltel-Euskadi 0:13:49
10 Benat Intxausti (ESP) Movistar 0:14:10