16:45 - Stage 16 result: 1. Cataldo, 2. De Gendt +7, 3. Rodriguez +2:39, 4. Contador +2:41, 5. Valverde +2:56, 6. Quintana +3:23, 7. Anton +4:06, 8. ten Dam +4:21, 9. Gesink +4:22.
0km - Chris Froome is pedalling squares as he approaches the summit and crosses the line 5:10 down on the winner - that's more than two minutes lost to his rivals.
0km - Rodriguez takes third place, 2:40 down on winner Cataldo. And Contador crosses two seconds back, plus will concede four bonus seconds as well.
0km - Back with the main guns: Valverde has caught the two best riders in this year's race - but then Contador puts in another dig with 500m to go. But Rodriguez now takes up the reins - and remember, there are some bonus seconds available for third place...
0km - De Gendt crosses the line six seconds back - he could not repeat his Stelvio heriocs.
0.1km - Just one hundred metres for Cataldo! Here he comes... he pumps his fist and takes the win!
0.2km - De Gendt is creeping back to Cataldo! This is cycling in slow motion!
0.3km - Cataldo has 10 seconds on de Gendt and will take the win - the biggest of his career.
0.5km - Valverde is starting to ride back on the wheel as Contador puts in yet another attack. But once again the red jersey had enough and manages to follow the white jersey.
0.7km - Cataldo looks like death on wheels but he still has 20 metres on de Gendt inside the final kilometre.
0.8km - Valverde can't deal with this steep 23% part - but Rodriguez is right on his shoulder and is not giving him any space.
1km - Quintana attacks from the chasing quartet! Movistar did this yesterday, paving the way for Valverde... Contador digs in to reply, and reels in the Colombian. And then passes by!
1.5km - Cataldo is begging to distance de Gendt!
1.5km - Cataldo leads de Gendt up a fiercely steep 23% section. This is a real battle of attrition.
2km - The leaders are onto the final segment with gradients as high as 22%. The fans are out in their masses, but still they ride together.
2.5km - Valverde doesn't manage to drop the others and he's back with Rodriguez, Contador and Quintana.
2.5km - The Froome group is 45 second back. And this is impressive: Valverde puts in an attack himself and opens up a small gap.
3km - Back with the leaders, de Gendt and Cataldo are still together as they pass the 3km-to-go banner. They are 2km ahead of the chasing four riders.
3.5km - Great stuff from Valverde and Quintana: the Movistar pair are returning onto the wheels of Contador and Rodriguez.
4km - Valverde has popped. Quintana is waiting for him and will try and pace him back. Rodriguez looks to be in a bit of pain behind Contador.
4.5km - Valverde and Quintana are struggling to keep up with Contador and Rodriguez. But they're hanging in on there.
5km - Contador makes his move! He jumps out of team-mate Pires's wheel and forces a reaction from the others.
5.5km - Rafal Majka of Saxo Bank cannot continue and peels off, leaving Contador with Pires. The tempo is increased and the race is blown apart again: only Rodriguez, Valverde and Quintana can keep up. Froome has been dropped.
6km - The leaders are onto a steep 15% section and it's de Gendt who is setting the tempo. Back with the chasing group, Saxo are riding hard. Rodriguez is still alone after both Menchov and Moreno cannot keep up with the pace - the Katusha pair are right on the back of the group.
7km - Still de Gendt and Cataldo ride together as they pass under the 7km-to-go banner. They are onto a 9% section with a lead of 5:40 over the chasing group. The gradient will be double that in the last ramp before the finish.
7.5km - The three top men in the Vuelta - Rodriguez, Contador, Valverde - are riding shoulder to shoulder. Contador has two Saxo team-mates in front of him. Rodrigues is still waiting for Menchov and Moreno. Valverde has two Movistar men behind him. They're on a shallower gradient - just 4% at the moment. Roche has blown: he's off the back again.
8km - Moreno, Menchov, Roche and Monfort rejoin the group of the main favourites. Rodriguez will be pleased to have two team-mates now after a long period of isolation.
9km - Still we have four Saxo Bank riders (including Contador) followed by Rodriguez, then three Movistar riders (including Valverde) and then Froome. The rest are just hanging in. Moreno is being paced back by Menchov, alongside Roche, in a small group about 10 seconds back.
10km - The two leaders pass under the 10km-to-go banner. They have 5:50 over the chasing main group.
11km - There are about 16 riders in this main group - and only one from Katusha. Rodrigurz is very isolated - and there are even rumours from the Belgian press that he has a fever today. Irish fans, Nicolas Roche is not in this group.
12km - Nairo Quintana of Movistar edges off the front of the peloton - this is the same tactic that Movistar used yesterday. He's reeled back in by Paulinho. Also in this group: Froome, Talansky, Uran, Rodriguez (who is alone it seems, without Katusha right-hand man Moreno), Anton, Gesink, ten Dam...
13km - Contador is now down to just three team-mates - Paulinho and Hernandez - after their fierce pace-setting. Daniel Navarro, his jersey undone to reveal a white pasty chest covered with a spattering of fuzz, is the latest to pull off and drop back, his work for the day done.
14km - Saxo have really forced a selection - just 20-odd riders left now, including the Big Three Spaniards and Chris Froome. The leaders have 6:48 so should be okay in spite of this serious upping of the tempo.
15km - The Euskaltel pair peel off and allow Saxo Bank to take up the reins on the front. They have Sky right threre too. Saxo are causing some major damage on the early part of this final climb. Multiple riders are being blown off the back.
16km - Richie Porte (Team Sky) picks up a puncture and needs a front wheel change. Bad timing for the Tasmanian, who will need to fight back on ahead of the final climb, which the peloton is fast approaching.
17km - The six-man Bouet-Mate group is swept up. It was always rather ambitious. Our two leaders - Italian Dario Cataldo (OPQS) and Belgian Thomas de Gendt (Vacansoleil-DCM) - are 7:38 further up the road and on the final climb of the day. De Gendt is overwhelming favourite for today's stage after his heroics in the Giro.
18km - Euskaltel have two men on the front. We then have Saxo Bank and Team Sky, both almost in their entirety. Valverde has two Movistar team-mates and Rodriguez has three Katusha team-mates. That splinter chasing grioup is about to be caught.
20km - The leaders are onto the HC Valgrande-Pajares climb (20km at 6.9%).
20km - The main pack is still 8:12 down on the two lone leaders, Cataldo and de Gendt, one of whom will surely win today's stage.
22km - The six-man chasing group - Mate, Bouet, Gerdemann, Bakelants, de Weert and Zeits - have 45 seconds on the pack now.
23km - Saxo Bank are still on the front, with white jersey Alberto Contador now back with his team-mates. They won't be too concerned about that counter attack because it includes no threats and no top drawer climbers.
24km - Four more riders have pinged off the front of the peloton: RadioShack pair Linus Gerdemann and Jan Bakelants, Omega Pharma-QuickStep's Kevin de Weert and Astana's Andrey Zeits.
25km - Luis Angel Mate (Cofidis) and Maxime Bouet (Ag2r-La Mondiale) have jumped clear of the peloton on the descent.
28km - By taking those two Cat.1 climbs, Thomas de Gendt has moved to 23 points in the KOM standings, which is enough for fourth place. If he wins tonight, he'll be in the reckoning for the polka dot jersey.
30km - The final climb today, the HC ascent of Cuitu Negru, is the eighth and potentially most decisive of all the Vuelta's ten summit finishes. It's 23.5km long because of an extra 2.8km track that has been added at the end, once the initial climb reaches the Pajares ski station. The last segment is being used for the first time ever in the Vuelta and the surface has been paved with concrete slabs with sections as high as 25%.
33km - Saxo Bank lead the main pack over the summit of the climb 7:43 down on the two leaders, who are half way through their long descent ahead of the final deciding climb.
35km - More bizarre scenes: Sky and Saxo have pulled off the front of the main pack, but without Froome, who's either bluffing or is looking very much on the ropes. He could, of course, merely be curios to see what the other Big Three riders are doing at the back.
40km - This is certainly very strange seeing Contador, Rodriguez and Valverde all riding on the back of the main pack. They clearly don't trust each other and want to stick together.
41km - The two leaders are approaching the summit - and Thomas de Gendt takes the points ahead of Dario Cataldo. They have 8:25 over the peloton, so the gap is coming down. But it should still be enough.
42km - Rodriguez now rides with Moreno and Menchov, while Contador sits in their wheel. Valverde, in green, is also there. It's a strange tactic from Contador, whose team-mates are still setting the pace on the front, 30 metres further up the road, alongside Sky and Chris Froome. This peloton has been whittled down to about 60-odd riders now.
43km - Saxo Bank have a big hold on the peloton now, driving along the pace with white jersey Alberto Contador tucked in just ahead of a long line of Team Sky riders. Red jersey Rodriguez is still quite far back alongside Katusha team-mate Dani Moreno. It's something that seems to be confusing Contador, who pulls wide out of the peloton and then drops right back to tuck himself behind his big rival.
44km - The peloton has now caught GreenEdge pair Pieter Weening and Simon Clarke, who broke clear towards the summit of the last climb in a bid to secure some mountain points for Clarke, the current polka dot jersey.
45km - The lead drops below the 10-minute mark as the pace begins to pick up in the peloton. Numerous riders are struggling to keep up and are beginning to drop off the back one by one. Red jersey Joaquim Rodriguez is acually very far back, although it looks like he just went back to see his team car.
46km - This stage has Thomas de Gendt written all over it - and the fact that both he and Cataldo are so far down on GC will act in their favour. In the Giro, de Gendt almost overturned Joaquim Rodriguez's lead in the GC with his ride up the Stelvio. This time round, Purito can relax: the Belgian is more than an hour down on GC.
48km - The gap is coming down a little - 11:45 at the latest check. Euskaltel continue to drive the pace in the peloton for their man Igor Anton, who is 11th on GC. "Yesterday was very hard. I felt okay but then when the battle started I struggled. I think I can still get as high as seventh on the GC but I would like to get a stage win," Anton said this morning.
49km - Mikel Astarloza and Ruben Perez (Euskaltel) are still setting the pace in the front of the peloton. Omega Pharma-Quick Step have come alongside Saxo Bank - probably to act as a disrupting influence, given the presence of their man Cataldo further up the road.
50km - De Gendt and Cataldo are onto to Cat.1 Alto de La Cobertoria (8km climb at 8.6% and a total rise of 692 metres).
52km - Euskaltel are driving the pace on the front of the peloton - the Basque Boys in Orange have a couple of men on the front ahead of Saxo Bank, and another couple further back. Perhaps Igor Anton is feeling strong today.
55km - The two leaders are approaching the penultimate climb of the day with a lead of 12:40. They are taking it in turns to pull on the front, combining very well.
58km - There was an intermediate sprint at the foot of the last climb, which was won by de Gendt ahead of Cataldo. Around 13 minutes later, Weening picked up the last point for third place. No changes in the points classification, which Rodriguez still leads. The Spaniard has 148 points to Alejandro Valverde's 127 - but it is Valverde who wears the green jersey because Purito is in red.
60km - Saxo Bank-Tinkoff lead the chase with a couple of Euskaltel riders lending a hand. They have reached the end of the steep part of the descent. The gap is stable - just over 13 minutes still. Pim Ligthart (Vacansoleil) and Kevin Seeldraeyers (Astana) managed to zip clear of the bunch on the early part of the descent but they were reeled in.
65km - Cataldo and de Gendt have a bite to eat as they approach the end of the descent. It's not very steep and they're taking shifts on the front. Their advantage is 13:10 so they're looking good to contest the overall win - although we still have two more climbs, and they will need at least four minutes, possibly even five, at the foot of the final climb - which is 20km long.
68km - Confirmation of the points over the Cat.1 Puerto de San Lorenzo: 1. De Gendt (10pts), 2. Cataldo (6pts), 3. Clarke (4pts), 4. Weening (2pts), 5. Moncoutie (1pt). That consolidates Clarke's lead in the KOM standings. He leads Rodriguez by 38 points to 30.
70km - Weening leads out the uphill sprint for Clarke - and they have too much for Moncoutie, who has to settle for fifth place. The peloton crosses the line 30 seconds later. They trail our two lone leaders Cataldo and de Gendt by 13:15.
71km - GreenEdge are pacing their man Simon Clarke up in a bid to snare the remaining mountain points. David Moncoutie is lurking too - and the Frenchman pings off the front, with Clarke and team-mate Pieter Weening in tow. David de la Fuente of Caja Rural tries to follow but doesn't have it in him.
75km - De Gendt and Cataldo are well onto their descent now. Still no confirmation of the order over the top of the climb. The peloton is approaching the summit now, with Saxo Bank, GreenEdge and Movistar all near the front.
80km - The leaders cross the summit of the Cat.1 Puerto de San Lorenzo with a gap of around 14 minutes.
84km - The gap comes down a little to 14:28 now that the Saxo Bank team of Alberto Contador is putting in a shift on the front of the peloton. Euskaltel are there as well. The Basque team are still looking for their first stage win of the race.
85km - Dutchman Robert Gesink (Rabobank) is sixth on GC, 5:42 in arrears. "In theory, today's stage could be favourable to me. Yesterday I felt much better than on Saturday. I'm feeling better day by day and I hope that it will continue like that," said Gesink this morning.
86km - Team Sky's Chris Froome suffered an off-day yesterday, conceding 35 seconds to his main rivals and dropping to fourth on GC, 2:16 off the top. "This morning I feel in form and much better than I did yesterday. I am ready to fight," he told reporters at the start of today's stage.
88km - The gap is up to 15 minutes now so it's looking good for these two riders. Back with the bunch, Pablo Lechuga of Andalucia gets off his bike and calls it a day. The Spaniard was involved in a break in the first week but has had clearly enough of these mountain stages.
90km - The gap is up to 13:30 for the two leaders as they combine well on this first Cat.1 climb.
92km - Our two leaders Thomas de Gendt and Dario Cataldo are onto the Cat.1 Puerto de San Lorenzo (10km climb at an average gradient of 8.5% and a total rise of 850 metres). They have 11:45 over the peloton.
96km - The speed of this stage has been very high, considering what we still have in store: 44.7 km/h for the second hour of racing. De Gendt and Cataldo are approaching the second climb of the day...
98km - The lead of the two escapees is up to 11:25 as green jersey Alejandro Valverde (Movistar) needs to drop back to his team car for some mechanical assistance.
100km - Belgian Thomas de Gendt finished third in this year's Giro after his remarkable solo win atop the Stelvio in stage 20. The 25-year-old all-rounder also won stage seven of Paris-Nice this year. De Gendt missed the Tour de France because he was getting married to his girlfriend - and the pair will finally get to go on their honeymoon after the Vuelta. This is his first appearance in the Vuelta and the second break he's been involved in after a disappointing opening week in the fierce heat.
102km - The gap is now almost eight minutes for the leaders, who are combining very well ahead of the three big climbs of the day. Javier Aramendia, the Caja Rural who was so attacking in the opening 10 days of the race, needs to see the race doctor. BMC's Yannick Eijssen too seems to have a problem.
105km - Italian Dario Cataldo joined Quick Step from Liquigas in 2009 and is the current national time trial champion. The 27-year-old won two stages in the 2007 Tour de l'Avenir and the GP Beghelli in 2010. But he's one of those riders yet to really achieve his full potential. This is his third Vuelta - he finished 71st in 2010 and 132nd in 2011.
110km - The gap is growing crazily fast now: five and a half minutes for de Gendt and Cataldo.
115km - Neither of these two escapees are a threat to Joaquim Rodriguez on GC: they are both more than an hour down in the overall standings. The gap is nearing three minutes now.
120km - De Gendt and Cataldo are combining well and have a lead of more than two minutes now. This looks very promising - and we all know what the Belgian de Gendt is capable of: he won the queen stage of the Giro with a blistering ride atop the Stelvio, setting himself up for a podium finish while at it.
128km - The two leaders have around 30 seconds on the peloton. The road rises steadily now until the first of two back-to-back Cat.1 climbs ahead of the final HC ascent.
132km - Thomas de Gendt (Vacansoleil-DCM) and Dario Cataldo (Omega Pharma-Quick Step) ping off the front.
135km - it's been a very fast start to today's stage with an average speed of 46.1 km/h for the first hour. It was predicted that the peloton would ride along at around 37 km/h.
138km - French veteran David Moncoutie (Cofidis) jumps clear to take the three points over the summit ahead of Javier Moreno (Movistar) and Gianni Meersman (Lotto Belisol). Moncoutie has won the king of the mountains classification for the past four years but he will have his work cut out to repeat the feat for a record fifth successive time this year. Simon Clarke (Orica-GreenEdge) is the current blue polka dot jersey, leading Joaquim Rodriguez by four points.
140km - It looks like this first climb is going to be a mere routine ascent, a small hors d'oeuvre to tick off en route to the main meal. The peloton rides as one, with Sky controlling matters.
141km - Nico Sijmens (Cofidis) and Sergio Paulinho (Saxo Bank) edge off the front but are reeled back by the pace-setting of Team Sky.
142km - We're onto the first climb of the day, the Cat.3 Alto de la Cabrunana (4.4km at 5.7% and a rise of 225m).
145km - Garmin-Sharp were one of the teams caught out by that split - but the American team have managed to bring it all back together. There was around 20 seconds splitting the two parts of the peloton, with Movistar particularly prevalent in the leading group. It's all back together and that opening climb is coming right up.
148km - One rider did not take to the start today: Australian Cameron Meyer of Orica-GreenEdge. Meyer was riding an aggressive race and finished second in stage 12 as well as featuring in a couple of other breaks, plus taking a top ten in the ITT.
150km - There's been a big split in the peloton on this fast approach to the opening climb of the day. Around 50 riders are in the first group.
158km - It's pretty short-lived as Henao and Garcia are swept up by the pack.
160km - Two more riders have jumped off the front of the pack: Egoitz Garcia of Cofidis and Sergio Henao of Team Sky. This is interesting - either the Colombian Henao is trying to set up Chris Froome for later, or Team Sky have given up on their British rider, who slumped to fourth place on GC yesterday after losing 35 seconds to the Big Three at the finish.
164km - El Cuitu Negru, the final monster climb, is covered in fog but expected to clear by the time the riders reach it this afternoon.
168km - The pelelton is very active, but no one else has broken away as yet. A series of blistering attacks by Alberto Contador on the emblematic Lagos de Covadonga climb failed to dislodge Joaquim Rodriguez on Sunday - but the red jersey said he was right on the limit in defending against them. Contador made Rodriguez suffer with '32, 33 attacks'
173km - And they are back in the main body of riders. The final climb today is 20km long, averaging a gradient of 6.9% with a maximum greater than 22%.
174km - He is joined by four other riders - Egor Silin (Astana), Remi Pauriol (FDJ-Big Mat), Alexandre Geniez (Argos-Shimano) and Marcos Garcia (Caja Rural) - seven seconds ahead of a peloton led by Euskaltel-Euskadi, Movistar and Andalucía.
178km - Tiago Machado (Radioshack-Nissan) with a lone escape.
182km - Pim Ligthart (Vacansoleil-DCM) leads an immediate break that is swallowed back up by the peloton sharpish.
184km - Today's stage is under way near the Cantabric Sea. In the standings, Joaquim Rodriguez leads Alberto Contador by 22 seconds with Alejandro Valverde moving up to third, 1:41 down, after British hope Chris Froome (Team Sky) lost 35 seconds on the final ascent yesterday to drop to fourth in the overall standings, 2:16 in arrears. General classification
12:20 - Yesterday, Spain's Antonio Piedra secured the biggest win of his career at Lagos de Covadonga as Chris Froome lost more ground in the mountainous stage 15. The unheralded Piedra attacked from a 10-man breakaway on the final climb of the 186.5km stage in northern Spain to take a first ever Vuelta stage win for his Pro Continental second tier Spanish team Caja Rural. Piedra wins, Rodriguez keeps red after Vuelta stage 15
12:15 - Stage 16 is the most important of this year's Vuelta, featuring two Cat.1 climbs before a HC summit finish in Valgrande-Pajares.