Tom Dumoulin comes home 7:30 down on the stage winner, a broken man. He's out of the top five and lashes out at reporters swarming around him.
San Lorenzo de El Escorial - Cercedilla
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Euphoric scenes at the finish line - Aru is in floods of tears and swamped by team-mates, Astana staff and journalists.
And here comes the Aru group, led by Rodriguez in green. Chaves nips ahead of the Spaniard, then it's Aru punching the air alongside Sanchez. He has won the Vuelta a Espana.
Here comes the Majka group - the Pole crosses the line 2:46 down in a group of escapees and Quintana, a few seconds back.
Astana riders already punching the air - they know Aru has won this Vuelta.
Goncalves takes second place ahead of De Marchi around 1:06 down.
Ruben Plaza (Lampre-Merida) attacked from 114km out to win his second Grand Tour stage of the season after his scalp in the Tour de France in July...
Plaza takes off his gloves and tosses them into the crowd before crossing the line with his arms aloft. What a win!
Under the flamme rouge for Ruben Plaza - and he's onto the rise to the line now. He has 1:15 so will be ok.
Rodriguez risks losing his second place to Majka at the moment because of the gap to the Pole and Quintana. He drives the chase accordingly.
Goncalves and De Marchi are really giving it some throttle but the gap is not coming down.
Plaza's lead is down to 1:25 but he still looks on course for the win. Amazing considering he attacked solo more than 100km ago!
Plaza has 1:30 over his chasers, 4:00 over Majka and Quintana and 7:45 over Dumoulin. He's about to finish the plateau and head downhill towards a near certain victory.
And now the Aru group comes over the summit 5:00 down.
Quintana and Majka have reached the summit 4:26 down on Plaza. The Pole will be on the podium tomorrow.
The gap back to Dumoulin from the Aru group is now 3:10 so Dumoulin could well drop out of the top five today.
Goncalves and De Marchi pass through at 1:40 ahead of Visconti and then a returning Henao.
Ruben Plaza crests the summit for another 10pts in the KOM competition - he can almost taste the victory now... He has 7km false flat and then the downhill ride to the finish. There's a little ramp before the line but as long as he maintains some of this gap, he'll be ok.
ATTACK: Quintana bounds clear of the Aru group, taking Majka with him. They're both battling for podium positions.
Goncalves has rejoined De Marchi and Visconti. They're 1:28 down on the lone leader Plaza now, and approaching the summit.
To make matters worse for Dumoulin, Astana's Zeits has been dropped by the Aru group and is now sandbagging the Dutchman. The gap is 1:40 for the red jersey, who will almost certainly drop off the podium today.
Italian duo Visconti and De Marchi have reeled in Goncalves - and the Portuguese is struggling to hold on now as the BMC rider ups the tempo.
Jose Goncalves attacks from the chasing quartet and rides clear in pursuit of Plaza, who still has 1:40. What a ride this is from the Spaniard - but his Portuguese pursuer may have fresher legs here... exciting stuff.
Dumoulin and Nieve have dropped Howes. They're on the final climb of the day - well, the leaders are - the Cat.1 Puerto de Cotos (10% at 5.5%).
Meanwhile, Visconti and De Marchi have been joined by Montaguti and Goncalves, so we have a chasing group of four in pursuit of Ruben Plaza, the lone leader. The Aru group is seven minutes down, and Dumoulin a further 1:20 in arrears.
Dumoulin and Nieve have caught Alex Howes from the break. Three is better than two - and there's another one further up the road. A dog just walked across the road - a black dog too. Poor Dumoulin...
Rodriguez also has Katusha team-mate Vorganov, who has sat up from the break. The Spaniard will be eyeing the second place on the podium tonight - it's that bad for Dumoulin.
Aru now has Zeits and Sanchez as well as Landa after the breakaway duo slowed to lend a hand from the front. The plan is coming together perfectly for the Kazakh team.
Dumoulin is shaking his head now. He knows that the Vuelta is slipping through his fingers. The gap is growing and growing - 35 seconds now.
Dumoulin asking Nieve to come through - he's really on the edge of his powers. The gap is back up to 20 seconds as they pass through the intermediate sprint, which presumably was won by Plaza, not that it matters.
Back with the lone leader and Plaza has 1:210 over the two chasers De Marchi and Visconti, and nine minutes over the Aru-Rodriguez group.
Just 12 seconds now for Dumoulin, who is getting back into his groove. But how will he cope on the next climb with no team-mates or allies? The cards are stacked in Astana's favour what with Landa there as well as Aru. What's more, they have help further up the road in Sanchez and Zeits.
Dumoulin looks in real trouble here. The gap is still only 20 seconds but he looks very uncomfortable on the bike and is cornering this descent really badly. He's drinking a lot and could well have bonked.
Dumoulin is tackling the descent alongside Nieve with a 20 second deficit on the Aru group. What drama.
Landa, Chaves and Rodriguez have joined the Aru trio but Dumoulin has been distanced ahead of the summit.
ARU ATTACK! The italian rides clear with Quintana and Majka!
Valverde has cracked! The Spanish national champion has been distanced by this select group of main GC favourites and he'll have to finish this climb on his own before chasing back on on the descent.
Dumoulin has closed the gap, joining the two select groups together. Good effort from the rangy Dutchman.
Plaza is over the top - and it's Visconti who leads De Marchi over 1:45 in arrears.
Quintana and Majka are with Landa and Aru. They have 2 seconds on a group being led by Dumoulin that includes Rodriguez, Valverde, Chaves and Nieve.
Now Aru comes to the front with Landa and they've upped the tempo considerably. There's a small gap back to Dumoulin!
Visconti have been joined by De Marchi in their pursuit of Plaza. Astana are now on the front of the pack with Tinkoff-Saxo and Katusha.
Numerous riders off the back of the peloton already on this climb. Remember - they're riding a full 12 minutes behind the lone leader, Ruben Plaza. The Spaniard still has 2:20 over the chasers, who have Visconti out just ahead.
After a flurry of attacks in the break, it's now Giovanni Visconti who has edged clear for Movistar.
Back with the main pack and it's Astana's Dario Cataldo who leads alongside a couple of Movistar riders and Giant riders. The big guns keeping their powder dry for now.
Kenny Elissonde now stretches his legs for FDJ. Bennett is in pursuit before Sergio Henao takes it up.
Now Bennett attacks - and he's being pursued by a BMC rider and then Ventoso and Dombrowski. They're going to bring him back. Plaza now has 2:48 so riding very well.
Reza has been caught and past as George Bennett (LottoNL-Jumbo) and Joe Dombrowski (Cannondale-Garmin) set a fast tempo.
Cannondale-Garmin are active in this chasing group, which has shed a few riders now the gradient has gone up again. Reza still out ahead in pursuit of lone leader Plaza.
Plaza is onto the second ascent of the Cat.1 Puerto de Morcuera. Reza actually managed to edge clear of the chasing group a second time lucky so the rangy Parisian is in pursuit. The pack is still 12 minutes down.
The road is heading up but the third climb has not yet officially started for Plaza. MTN still drive the pace in the pack.
The MTN-Qhubeka team of Louis Meintjes have come to the front of the pack to help lead the chase. That's because Frenchmen Romain Sicard and Kenny Elissonde - both in the break - are a threat to his 10th place on GC. Europcar's Sicard is 19:21 down and FDJ's Elissonde is 19:36 down - but with the 10-odd minutes they have today, that puts them within a couple of minutes of the top ten.
Plaza's lead is up to 2:10 over the chasers and 12:20 over the main peloton. It's the quiet before the storm.
Kevin Reza of FDJ is the latest of the escapees to have a dig from the chasing group. Zubeldia was brought back, as is Reza.
Plaza still has 1:45 over the chasers after stretching the lead back out. He's looking good but still may pay for it on the next two climbs.
Haimar Zubeldia (Trek) has edged ahead of the chasing group, which has come back together again after those earlier splits. The Basque veteran led the stage that Joaquim Rodriguez won last week right until the last couple of kilometres. He also got pipped by Nico Roche for the win two days ago. He has since signed a new contract with Trek for next season so is clearly feeling up for this.
The next categorised climb is in fact the previous one done in reverse - the Cat.1 Puerto de la Morcuera.
The chasing group has split up, which is no surprise because it's just way too large to be effective as it is. Plaza is on that uncaterorised mound now - the Alto Cerro San Pedro - with an advantage of one minute over the nearest chasers. "He's bitten off more than he can chew going off so early," says Sean Kelly.
Plaza's lead has dropped to under two minutes now that the road has levelled out following the descent. There's an uncategorised mound ahead of the next climb so it will probably come back together soon. Back with the pack, some of the pretenders to the crown will have to do something on the next Cat.1 climb or it will be too late - so expect fireworks in about 45 minutes.
So, those 38 chasers are: Adam Hansen (Lotto-Soudal), Jaco Venter (MTN-Qhubeka), Lawrance Warbasse (IAM), Dani Navarro (Cofidis) Jay McCarthy (Tinkoff-Saxo), José Gonçalves (Caja Rural), Eduard Vorganov (Katusha), Moreno Moser (Cannondale-Garmin), Yukiya Arashiro (Europcar), Kevin Reza (FDJ), Andrey Amador (Movistar), Haimar Zubeldia (Trek), Carlos Quintero (Colombia), Joe Dombrowski (Cannondale-Garmin), Alexis Gougeard (Ag2r-La Mondiale), Sergio Henao (Team Sky), Andrey Zeits (Astana), Giovanni Visconti (Movistar), George Bennett (LottoNL-Jumbo), Luis León Sánchez (Astana), José Joaquín Rojas (Movistar), Pello Bilbao (Caja Rural), Nelson Oliveira (Lampre-Merida), Alberto Losada (Katusha), Matteo Montaguti (Ag2r-La Mondiale), Alessandro de Marchi (BMC), Valerio Conti (Lampre-Merida), David Arroyo (Caja Rural), Kenny Elissonde (FDJ), Alex Howes (Cannondale-Garmin), Carlos Verona (Etixx-QuickStep), Amael Moinard (BMC), Nicolas Roche (Team Sky), Jelle Vanendert, Jasper De Buyst (Lotto-Soudal), Alex Cano (Colombia), Romain Sicard (Europcar) and Fran Ventoso (Movistar).
David Arroyo (Caja Rural) has crashed on the descent and is waiting for a new bike. He'll have to fight back on to the break now - and that will dent his chances of entering the top ten today.
Some riders having a few bothers on the descent, with Russian Vorganov (Katusha) leaving the road on a tight bend, riding onto a gritty parking bay but managing to stay up before rejoining the road ahead of the commissaire's car. That was a close one.
Plaza has 2:30 on the 37 chasing riders and 11:15 over the pack, which is still being led by the Giant-Alpecin team of Tom Dumoulin.
The chasing groups have come together so we now have 37 riders in pursuit of lone leader, Plaza. The Spaniard goes over the top in pole position, which puts him on 33 points and that's second place behind Omar Fraile in the KOM standings. Fraile's lead of 82 cannot be beaten today, however.
A reminder of the nine chasing riders who are about 20 riders behind: Adam Hansen (Lotto-Soudal), Jaco Venter (MTN-Qhubeka), Lawrance Warbasse (IAM Cycling), Dani Navarro (Cofidis), Jay McCarthy (Tinkoff-Saxo), José Gonçalves (Caja Rural-Seguros RGA), Eduard Vorganov (Katusha), Moreno Moser (Cannondale-Garmin) and Yukiya Arashiro (Europcar).
Attack by Ruben Plaza of Lampre-Merida. He won a stage in the Tour and now the veteran Spaniard is going for a long one, edging clear of the leading group of 10 riders.
We're onto the second climb of the day, the Cat.1 Puerto de la Morcuera (11.5 km at 5.4%). There's now one minute between the two leading groups, with the peloton 9:40 back.
The best placed rider in the two breaks is Spaniard David Arroyo of Caja-Rural. Before yesterday's stage he was 30 minutes down on GC, but he halved that yesterday and is currently 14:49 down on Dumoulin. But with the six-odd minutes he has today, he's not virtually up into the top ten.
There's no cohesion whatsoever in the chasing group, which contains four stage winners from this year in Roche, Oliveira, De Marchi and Gougeard.
No change in the time gaps on this long forested descent. The leaders have actually got to the bottom and they're passing through a little town with cobbled streets.
With four riders up ahead, Movistar's tactics are clear to see. They're clearly planning something with Valvarde and Quintana today, and they'll have support up the road when they do so. If they can't get either man on the podium then a stage win wouldn't go amiss. They only have one win from this year's Vuelta - Valverde back in the opening week.
The 11 leaders have 45 seconds over the large chasing pack, with the peloton now a large 7:25 down on this descent.
Giant-Alpecin still control matters on the front of the peloton. They have no riders in either of the breaks - which is no surprise: today is not about attacking but defending the race lead of their man Tom Dumoulin.
It was José Gonçalves who took the 10pts atop the first climb in the break, protecting the already unassailable lead of his Caja Rural team-mate Omar Fraile in the KOM standings. Plaza was second ahead of Warbasse, Moser and Navarro. Moreno Moser (Cannondale-Garmin) actually replaced Miguel Ángel Rubiano (Colombia) in the lead group earlier on the climb when the Colombian rider tailed off.
It's worth adding that Fabio Aru will not receive any time penalty for an alleged hand-sling he received from Luis Leon Sanchez yesterday on the final climb to the finish line. TV pictures were inconclusive and the race jury cast a blind eye over what would have been an illegal manoeuvre. The usual penalty for such a crime is 10 seconds. Read more about it below in the daily Vuelta Skelter blog...
The 29-man chasing group in full: Kevin Reza (FDJ), Andrey Amador, Fran Ventoso (Movistar), Haimar Zubeldia (Trek), Carlos Quintero (Colombia), Joe Dombrowski (Cannondale-Garmin), Alexis Gougeard (Ag2r-La Mondiale), Sergio Henao (Team Sky), Andrey Zeits (Astana), Giovanni Visconti (Movistar), George Bennett (LottoNL-Jumbo), Luis León Sánchez (Astana), José Joaquín Rojas (Movistar), Pello Bilbao (Caja Rural-Seguros RGA), Nelson Oliveira (Lampre-Merida), Alberto Losada (Katusha), Matteo Montaguti (Ag2r-La Mondiale), Alessandro de Marchi (BMC), Valerio Conti (Lampre-Merida), David Arroyo (Caja Rural-Seguros RGA), Kenny Elissonde (FDJ), Alex Howes (Cannondale-Garmin), Carlos Verona (Etixx-Quick Step), Amael Moinard (BMC), Nicolas Roche (Team Sky), Jelle Vanendert, Jasper De Buyst (Lotto-Soudal), Alex Cano (Team Colombia), Romain Sicard (Europcar).
Some interesting names in the chasing group: Sicard for Europcar, Visconti, Amador, Ventoso and Rojas for Movistar, Sanchez and Zeits for Astana, Henao and Roche of Sky, De Marchi of BMC and yesterday's winner Gougeard of Ag2R-La Mondiale.
We're onto the Cat.1 Puerto de Navacerrada (9.4 km at 6.6%). The leaders have 30 seconds on the chasing group and five minutes on the peloton.
A large group of around 30 riders is chasing the leading group. None of the big names are involved - they're keeping themselves primed for the later climbs, where the GC battle will no doubt intensify.
A small crash in the pack brings down Simon Gerrans (Orica-Greenedge) and Fabrice Jeandesboz (Europcar) amongst others.
The 11 leaders are: Ruben Plaza (Lampre-Merida), Larry Warbasse (IAM Cycling), Olivier Le Gac (FDJ), Adam Hansen (Lotto Soudal), Jaco Venter (MTN-Qhubeka), Dani Navarro (Cofidis), Jay McCarthy (Tinkoff-Saxo), José Gonçalves (Caja Rural-Seguros RGA), Eduard Vorganov (Katusha), Miguel Angel Rubiano (Colombia) and Yukiya Arashiro (Europcar).
It's a feisty start as Sylvain Chavanel (IAM Cycling) has an early dig before a group of 11 manages to open up a small gap.
One non-starter today: Jérôme Coppel (IAM Cycling), who was part of the break yesterday. That means 159 riders took to the start at the ornate palace of El Escorial.
Just six seconds separate Dumoulin in red and his nearest rival, Aru. Joaquim Rodriguez is 1:26 down in third place so it's all to play for today.
Yesterday Tom Doumoulin doubled his lead over Fabio Aru with a big dig on the punchy cobbled rise into Avila as French youngster Alexis Gougeard won stage 19 from a break of 24 riders.
Hola and welcome to live coverage of stage 20 of the Vuelta a Espana - and it's the big one: four Cat.1 climbs in a 176km ride from San Lorenzo de El Escorial to Cercedilla.