16:50 - Rodriguez is one second ahead of Contador, 16 seconds clear of Froome and 59 seconds ahead of Valverde. The Big Four of the Vuelta still all within one minute - fascinating.
16:49 - Rordiguez's time difference to stage winner Frederik Kessiakoff was altered to 1:16, which means the Spaniard holds onto the red jersey by one slender second!
39.5k - Here's Joaquim Rodriguez - he needs to finish within a minute to hold onto the red jersey. The Katusha climber has ridden out of his skin today, and crosses the line in seventh place ... 1:17 down on Kessiakoff ... and exactly a minute down on Contador!
39.5k - Here comes a faltering Froome, who lost time on the climb. It's the third fastest time, ahead of Valverde, but below his rival Contador. It's 39 seconds down on Kessiakoff, the stage winner.
16:42 - Alejandro Valverde rode brilliantly to take provisional third, 1:08 down on Kessiakoff. Just two more riders to arrive - Froome and Rodriguez.
39.5k - Here comes Alberto Contador... it's a great ride, but not enough to take the win: he's 17 seconds down on Kessiakoff, who looks to have become the surprise winner of today's time trial.
39.5k - Robert Gesink crosses the line to take eighth place, 1:42 down on Kessiakoff. That should be enough to keep him in the top ten, for sure.
16:36 - The upper hand is definitely with Contador in his duel with Froome - the latest check is 26 seconds, the Sky rider clearly feeling his travails from the Tour.
16:34 - Rodriguez is still only 49 seconds down on Contador as he limits his losses on this descent. He's riding a very good time trial and will be well within contact of the summit tonight.
16:31 - Contador is gaining time on Froome on the descent - he's 20 seconds ahead now.
16:30 - Alejandro Valverde was only 37 seconds down on Kessiakoff at the second check - the time gaps are not as big as we had expected.
23.5k - Joaquim Rodriguez is 56 seconds down on Frederik Kessiakoff at the first check, so that's 54 down on Contador, who is not yet the virtual red jersey on the road.
23.5k - Chris Froome is slipping: the Briton is 18 seconds down on Kessiakoff at the second check after the climb, which puts him 16 down on Contador, who will probably be in the red jersey tonight.
23.5k - Alberto Contador can only post the second fastest time at the second check - two seconds down on Kessiakoff.
23.5k - Gesink has faded on the climb - the Dutchman sets only the 10th fastest time at the second check, more than a minute down.
39.5k - Andrew Talansky crosses the finish to set the fifth best time, 1:24 down on Kessiakoff of Sweden.
16:18 - Contador is really giving it his all. At the moment, he's four seconds faster than his rival Froome - who he is racing for the first time in Spain.
39.5k - Benat Intxausti (Movistar) set the second best time at the finish, 1:09 down on currently leader Kessiakoff.
16:14 - Eurosport commentator Dave Harmon: "I think Froome looks a little more laboured than Contador - not much, but a little more."
16:13 - Purito looks in a bit of discomfort. He's out of the saddle and has his mouth agape. Today is all about survival - he knows the mountains are better suited to his strengths and so will want to be in touch with the summit after today's test.
16:10 - The current virtual general classification has Rodriguez in red with Froome at 19 seconds and Contador at 21. This is going to be a thrilling tussle.
13.5k - Red jersey Joaquim Rodriguez is 39 seconds down on Contador at the first check. It's not good - but at least this uphill section should suit him better.
13.5k - Chris Froome is four seconds down on Contador at the first check ahead of the climb. We certainly have a race on our hands - and that man Kessiakoff, the current leader at the finish, cannot yet be discounted.
13.5k - Alberto Contador is fastest at the first check with a time of 16:22 - that's two seconds quicker than Kessiakoff, but with both Froome and Rodriguez still to come.
13.5k - Alejandro Valverde is 29 seconds down on leader Kessiakoff at the first check ahead of the climb.
13.5k - Robert Gesink has gone through the first check just six seconds slower than the leader Frederik Kessiakoff.
13.5k - We finally have a late time check for Talansky at the first intermediate check - and it's not great. The American is 34 seconds down on Kessiakoff.
15:55 - Froome looks to be motoring along this first section - but we'll no nothing concrete until the first time check at the foot of the climb.
23.5k - Movistar's Benat Intxausti sets the second best time at the second check, 27 seconds down on Kessiakoff.
15:52 - Red jersey Joaquim Rodriguez, the race leader, is the last to roll down the ramp. He put in a decent time trial in the Giro - if he can build on that, he might well be able to keep the red jersey today. But it's a big ask, considering the time gaps that we've seen so far at the finish.
15:50 - Chris Froome, the white jersey, is on course. He won't get many cheers today from the fiercly patriotic Spanish crowds...
15:48 - Off the ramp goes Alberto Contador. He's the big favourite for today alongside Chris Froome. Bert is using a 40mm thick wheel on the front and 80mm disk wheel on the back. We're still waiting for a first time check for Talansky.
15:46 - Alejandro Valverde, wearing the blue polka dot mountains classification jersey, is now on course. This next hour could make or break his Vuelta. The Spaniard has been on such strong form so far - if he can avoid disaster today, he could be in the reckoning for a podium finish in Madrid.
15:42 - We're about to enter into the top five now, with Robert Gesink primed to roll down the ramp. He's the third Rabobank Dutch rider in the top ten. On the back of this, Rabobank are winning the team classification.
15:35 - Laurens ten Dam follows his Rabobank team-mate Mollema. Then we'll have Igor Anton, Nico Roche and Dani Moreno.
15:30 - We're onto the top ten riders in GC now, leaving at intervals of two minutes. Bauke Mollema is first up...
39.5k - Kessiakoff is approaching the finish line now. This is a splendid time - he takes a whole minute and 15 seconds off Richie Porte's target time. The Swede is the new leader with a time of 52:36. It's a huge 1:39 quicker than Tony Martin. And the question is - will the likes of Froome and Contador be able to beat that? It's certainly not a given.
15:28 - Garmin-Sharp's Andrew Talansky is on course and approaching the first check soon. It will be interesting to see how the American time trial specialist fares - he's had a quiet race but this could be his chance to soar up into the top ten.
23.5k - Sweden's Frederik Kessiakoff is absolutely blitzing this course: the Astana man shaves a huge 41 seconds off Riche Porte's previous target time at the second check. 35:42 is the new benchmark over the summit of the Cat.3 climb.
15:22 - Chris Froome, who earlier recce'd the course in a Team Sky car behind Ben Swift, is now on the rollers and plugged into his iPod (One Direction?).
15:20 - Interestingly, Porte and Meyer were both eighth and ninth respectively at the first check, before posting the first and second best times at the second check and the finish.
15:15 - Alejandro Valverde is warming up on the rollers, sporting a fetching Union Flag watch and listening to his iPod (Santana, perhaps?).
39.5k - Tony Martin can only set the fourth-best time at the finish, 24 seconds down on leader Richie Porte.
39.5k - It's only the fifth best time at the finish for Thomas de Gendt, who's 35 seconds down on the current leader Richie Porte, whose time has in fact been confirmed as 53:51 - that's two seconds quicker than his fellow Australian, Cam Meyer.
13.5k - New best time at the first check: Frederik Kessiakoff of Astana starts the climb after taking seven seconds off Lars Boom's effort at 13.5km.
39.5k - DEAD HEAT: Richie Porte crosses the finish line in a time of 53:53, which is exactly the same as his compatriot Cameron Meyer. So we have a tie at the top between the Sky and Orica-GreenEdge riders.
23.5k - Belgian Thomas de Gendt has just set the third best time at the second check. He's 18 seconds down on Porte's target time.
23.5k - We now have two Australians leading at the second intermediate check, with Richie Porte powering into the lead. The Tasmanian set only the 7th best time at the first check, 14 seconds down on Cam Meyer, but a strong uphill segment saw Porte open up a 12-second gap over his countryman at the 23.5km mark. The new target time is 36:23. Can the Sky rider sustain this to the end?
14:30 - It's early days, though: only 73 of 193 riders have finished this time trial so far. All the big guns are still to come, with red jersey Joaquim Rodriguez the last to leave at 15:50 UK time.
23.5k - It's not a good day for Tony Martin: the German is 19 seconds behind the target time set my Meyer at the second check, atop the Cat.3 climb.
39.5k - Australian track specialist Cameron Meyer has set the new benchmark at the finish, beating Castroviejo's effort by 17 seconds. Orica-GreenEdge's Meyer crosses the line to post a time of remarkable symmetry: 53:53. Meyer was part of the breakaway in stage eight to Andorra - he was the last rider to be caught within a couple of kilometres of the summit finish.
13.5k - World time trial champion Tony Martin can only set the second best time at the first intermediate check: the German is one second down on Lars Boom's effort at the 13.5km mark ahead of the climb.
23.5k - Australian Cam Meyer (Orica-GreenEdge) has set the new best time at the second check following the Cat.3 climb. Meyer's target time of 36:35 took seven seconds off Castroviejo's effort. As for Lars Boom - the Dutchman may have set the best time at the first check, but he faded on the climb and is currently third behing Meyer and Castroviejo.
13:49 - Tony Martin, one of the pre-stage favourites, has just rolled down the ramp. The German world time trial champion should take the lead after his ride, but it remains to be seen if the Omega Pharma-Quick Step rider will have enough over the hilly course to stave off Messrs Froome and Contador.
39.5k - Liquigas rider Maciej Bodnar set the second best time at the second check and has just crossed the finish line also in second place, 1:04 down on current leader Jonathan Castroviejo.
13.5k - Local favourite Gustavo Cesar (Andalucia) passes the first check 18 seconds behind leader Martijn Keizer. Moments later, Dutchman Lars Boom (Rabobank) comes through ten seconds faster to set the new benchmark at the 13.5km mark.
13.5k - Dutchman Martijn Keizer (Vacansoleil) has shaved one slender second off Castroviejo's target time at the first intermediate check. It will be interesting to see if Keizer can sustain this on the climb.
13:30 - Many thanks for your online comments - an apologies for those slight hiccups. The climb is a rise of 447 metres and not (of course) kilometres; Rodriguez cannot be caught by Froome (but could well lose two minutes) because he starts afterwards - if we're looking at it like this, the more likely scenario is for Valverde (fourth) to be caught by Contador (third). Finally, Ignatiev's initial time at the second check has been ammended - it was posted incorrectly on race radio.
39.5k - Jonathan Castroviejo (Movistar) continues his brilliant ride to post the new best time at the finish: the Spaniard takes almost five minutes off Ignatiev to cross the line in a target time of 54:10. Dutchman Martijn Maaskant (Garmin-Sharp) is second best at the moment, a huge 3:36 down on the leader, whose time will take some beating.
39.5k - Russia's Mikhail Ignatiev is the first rider to finish this individual time trial. Despite starting fourth on the road, the Russian caught Cheng Li (Argos Shimano), Juan Jose Lobato (Andalucia) and Joost van Leijen (Lotto Belisol) during his ride. His target time is 58:04.
23.5k - Jonathan Castroviejo (Movistar) is having a storming ride: the Spaniard took almost four minutes off Ignatiev at the second check. He is currently leading after the climb at the 23.5km mark with a time of 36:42. Biel Kadri (Ag2R) is second at 1:47 and Steve Cummings (BMC) third at 3:10.
13:15 - Team Sky's Ben Swift is currently on the road. He's being followed in the team car by his team-mate Chris Froome. The Briton has never ridden this route before and so this will be an invaluable recce. By contrast, Alberto Contador is said to have visited the course eight times in the build up to this year's Vuelta. It will be interesting to see if this has a visible effect on the way they ride their ITTs.
23.5k - At the second check, Mikhail Ignatiev (Katusha) is the current fastest: 40.28 at the top of the climb puts the Russian 1:17 faster than Javier Aramendia (Caja Rural).
13.5k - Spain's Jonathan Castroviejo, who led Movistar over the line in first place to take the race's first red jersey after the team time trial in Pamplona, has crushed the previous best time at teh first check. The chrono specialists shaves 46 seconds off Martijn Maaskant's effort at 13.5km with a time of of 16:42. That will take some beating.
23.5k - Joost van Leijen has reached the summit of the Cat.3 climb to post the first time at the second check on 23.5km: the Dutchman rolls over in 42.45.
13.5k - Katusha's Mikhail Ignatiev, fourth down the ramp this morning, has the new best time at the first check: 17:32.
13.5k - Joost van Leijen, the first rider down the start ramp, has reached the first intermediate check at 13.5km in a time of 18:56. The Dutchman will now start the climb.
12:30 - One rider is leaving every minute at the momentl. This will continue until the top 20, who will leave at two-minute intervals. That could feasibly create a scenario where the red jersey Joaquim Rodriguez is caught by second-place Chris Froome. // CORRECTION: That, of course, cannot happen, seeing that J-Rod will be starting after Froome! Contador could, theoretically, catch Valverde, mind.
12:25 - Unlike the regular road stages, there are no time bonuses in this ITT - it's each man to himself.
12:20 - The climb rises through pine forests before a descent that is steep in places and involves several hairpin bends. The roads are narrow, making this rather technical. In short - not the kind of time trial favoured by the world champion Tony Martin. The German should still be up there today, though, but the favourites must be Froome and Contador.
12:15 - Today's 39.5km time trial is not a straight forward flat affair: the Cat.3 Monte Castrove starts at the 13.5km mark and lasts 10km with an average gradient of 4.4% and a maximum gradient of 8%. All in all, there's a 447m rise from Cambados to the summit, before the descent and run into Pontevedra. On paper, the ITT is quite similar to the first ITT of the Tour de France, which also features a climb.
12:09 - Joost van Linden has rolled down the ramp to get this ITT underway. No overnight withdrawals to report. The last rider, red jersey Joaquim Rodriguez, will not leave the starting gate until 15:50 UK time. We will bring you updates on the course and the times being set until full live coverage once the top 20 riders or so are on the road.
12:05 - The first rider to start today's time trial will be the 'lanterne rouge' Joost van Leijen at 12:09 UK time. The Dutch rider from Lotto Belisol is currently last on GC - 1:38:57 down on Rodriguez in 193rd place.
12:00 - Joaquim Rodriguez retained his red jersey but the Katusha rider is expected to lose the race lead today in the race against the clock. He is trailed by 53 seconds by Chris Froome (Sky) and by one minute by Alberto Contador (Saxo Bank) - and both riders are considerably stronger time triallists. General classification and stage results
11:55 - Yesterday, Germany's John Degenkolb took a fourth win in the Vuelta a Espana with a bunch sprint victory in stage 10 in Galicia. Degenkolb benefited from a superb lead-out from his Argos-Shimano train before powering to a commanding victory ahead of France's Nacer Bouhanni (FDJ-BigMat) and Italian Daniele Bennati (RadioShack) in the 190km stage from Ponteareas to Sanxenxo. Report: Degenkolb wins fourth Vuelta sprint scalp
11:50 - Welcome to live coverage of stage 11 of the Vuelta a Espana, the much anticipated 39.5km individual time trial from Cambados to Pontevedra.