16:22 - New top three on GC: 1. Nibali, 2. Evans +4:02, 3. Uran +4:12, 5. Scarponi +5:14, 6. Niemiec +6:09
16:21 - Top five today: 1. Nibali 44:29, 2. Sanchez +58, 3. Caruso +1:20, 4. Scarponi +1:21, Majka +1:25.
16:19 - Heartbreak for Samuel Sanchez who came so close to winning the stage before seeing his time totally destroyed by Nibali.
20.6km - Maglia rosa Vincenzo Nibali punches the air as he crosses the line to take the win by 58 seconds on Samuel Sanchez - and by doing so, cementing his lead at the top of the standings.
20.6km - Cadel Evans is out of the saddle and giving it his best shot - but the damage is done. He crosses the line 1:38 down on Sanchez in 24th place.
16:16 - Cavendish may keep the red jersey tonight because Evans will struggle to finish in the top 12.
16:14 - Nibali has almost caught Evans - this is an extraordinary ride from the Italian. A combination of that and a terrible ride from the Australian...
20.6km - It's the fifth fastest time for the Colombian, 28 seconds slower than Sanchez. He managed to close the gap over the second half, but that was not the ride he needed to put the pressure on Nibali.
16:13 - Uran next to finish - and he's suffered in this time trial...
20.6km - Here comes Michele Scarponi, the 2011 de facto winner. It won't be the winning time - that rain clearly affecting his ride on the second half of the test. The Lampre veteran crosses the line 22 seconds down in third place. Sanchez stays at the top.
20.6km - Przemyslaw Niemiec (Lampre) has had a solid ride today. The Pole crosses the line in ninth place, 58 seconds down. He won't rise or fall in the standings today.
16:06 - Nibali has put two minutes into Evans now as the rain gets heavier and heavier.
20.6km - Mauro Santambrogio has another off-day. The Italian, who won atop the Jafferau, comes home with the 20th best time, 1:35 down on Sanchez.
16:03 - Evans is currently 1:40 down on Nibali according to on course times. The Australian has not had a good day. He also needs to finish 12th or better to take the red jersey from Mark Cavendish's shoulders...
20.6km - Carlos Betancur (Ag2R-La Mondiale) approaches the finish now and he's dancing out of the saddle. The Colombian has slowed on the second phase of the TT - but only just. He comes home in fourth place, 34 seconds down, which means Majka moves back into the lead of the youth standings by two seconds. A fabulous duel we have there...
20.6km - Poland's Rafal Majka (Saxo-Tinkoff) comes home for third place, 27 seconds down on Sanchez. Great effort from the youngster - but it is enough to take the white jersey back from Betancur? We'll find out very soon...
15:58 - Robert Gesink had a pretty torrid time out there, crossing the line in 20th place and almost two minutes down on Sanchez. The Blanco rider could drop out of the top 10 tonight.
9.5km - Nibali is having a storming ride: he takes 30 seconds off Scarponi at the first check and is 1:23 ahead of Evans at the half-way stage.
9.5km - Evans is almost a minute down on Scarponi at the first check...
15:51 - It's raining quite hard now - just as Scarponi is on that small descent. He has to take some of the corners rather gingerly - and he (and the others) could lose time here.
9.5km - Rigoberto Uran is a full 48 seconds down on Scarponi at the split. He could well lose his podium place to the Italian today.
15:49 - At the finish, Sanchez, the current leader, said: "I'm happy. The legs are fine. It's a good result but not enough for winning the stage. The rain can change the scenario. The small descent can be hard."
9.5km - Michele Scarponi blasts through the first check with the best time, taking seven seconds off Sanchez.
15:46 - Vincenzo Nibali looks steady and composed on the lower slopes of this climb. He's probably the favourite to take the win today.
15:43 - It's hard to tell how Uran is doing because he always betrays no emotion on the bike. He just grinds away and makes it all look rather effortless - just like he did when winning that stage in week two.
15:42 - There's some light rain now falling on the big GC riders as they tackle this decisive uphill time trial.
9.5km - Majka and Betancur are having very solid rides: the Pole comes through the split just seven seconds down on Sanchez and then Betancur betters that by one second.
20.6km - Samuel Sanchez takes the lead with a new best time of 45:27 at Polsa - that's 22 seconds ahead of Caruso. Great effort from the Spaniard from Euskaltel.
15:33 - Down the ramp rolls the maglia rosa: Vincenzo Nibali faces his moment of truth - or, to be more precise, his 45-minute moment of truth.
15:32 - Reminder of the current top five at the finish: 1. Caruso 45:49, 2. Clement +16, 3. Cataldo +21, 4. Duarte +39, 5. Gastauer +54.
15:30 - Now it's time for Cadel Evans to get his time trial under way. The Australian is showing the kind of form that saw him win the Tour back in 2011. In doing so, he relied on the final time trial to overturn a deficit to Andy Schleck. Can the BMC man do the same today with Vincenzo Nibali?
15:28 - Rigoberto Uran (Team Sky) rolls down the ramp and around the velodrome to get his race against the clock under way. He has a lot of time to recoup - but his main aim will be to cement his place on the podium and protect it from Scarponi.
20.6km - New fastest man at the finish: Damiano Caruso (Cannondale) comes home 16 seconds faster than Clement to take the provisional lead.
15:26 - Lampre pair Prezymeslaw Niemiec and Michele Scarponi are both on the course now. Just the top three to start now.
20.6km - Impressive by the Italian veteran Danilo Di Luca, who pushes Duarte out of third place at the finish, just 15 seconds down on leader Clement.
20.6km - Third fastest for Colombian Fabio Duarte, who crosses the line 23 seconds down on Clement. As he does so, he chucks up a load of liquids that he must have downed during that last climb.
15:20 - Mauro Santambrogio, currently sixth on GC after losing one and a half minutes on stage 16, is down the ramp. He'll want to get back into the top five, possibly the podium, over the next few days in the mountains.
9.5km - Euskaltel's Samuel Sanchez is riding very well and takes a full 17 seconds off Cataldo's target time at the first split.
20.6km - Stefano Pirazzi (Bardiani Valvole) finished in 118th place more than six minutes down on the current leader, Stef Clement. But remember, he missed his start by around five minutes and so most of the time shipped was in his carelessness.
15:13 - Rafal Majka of Saxo Bank rolls down the ramp. He'll be out to beat Carlos Betancur of Ag2R-La Mondiale, who is his big rival in the race for the white jersey. The Pole currently trails the Colombian by five slender seconds. Betancur, seventh on GC, will be next to leave.
15:11 - Benat Intxausti is down the ramp. He was wearing pink for the last time trial, which was won by his Movistar team-mate Alex Dowsett. Since then, Intxausti has won a stage and team-mate Gio Visconti two stages. It's been a great race for the Spanish team, who normally keep their best back for the Tour and Vuelta.
20.6km - Seventh best time for Fabio Felline at the finish, just pushing out Vladimir Karpets. That was unxpected by the Italian, who is wearing a nice retro cap underneath his helmet.
9.5km - Italian Damiano Caruso (Cannondale) is second at the first split, just two seconds down on compatriot Catado.
15:06 - We're not on to the top ten riders as Dutchman Robert Gesink (Blanco) rolls down the ramp.
20.6km - Ben Gastauer (Ag2R-La Mondiale) goes third at the finish, 38 seconds down on Clement. Good stuff from the Luxembourg TT champion.
15:00 - Next up is Estonia's Tanel Kangert. Like Pellizotti, we're used to seeing him in his national road race champions jersey, but today the Estonian is in regular Astana baby blue. He could go well today - Kangert has been very solid in the hills this year.
14:58 - Franco Pellizotti is down the ramp and on his way. We're used to seeing the curly-haired veteran in his retro Italian national champions jersey - but today he's in regular Androni kit because Cataldo's the national TT champ.
20.6km - We knew Stef Clement was riding well, but that's impressive. The Dutchman from Blanco shaves five seconds off Cataldo's time to move into the lead at the finish. New target time of 46:05 for Clement.
20.6km - Tom Danielson of Garmin sets the second best time, 40 seconds down on leader Cataldo and 5 seconds faster than third place Capecchi. A good effort from the American.
20.6km - Massive effort by Sky's Dario Cataldo, who crosses the line 45 seconds faster than his compatriot Eros Capecchi to set the new fastest time in Polsa.
14:45 - Dario Cataldo, the Italian national time trial champion, will soon complete his effort and should move into the lead. He's going extremely well. In fact, he's almost reached Stef Clement, and the Dutchman himself was going very well... CORRECTION: That was not Clement, but Blanco team-mate Paul Maertens.
20.6km - Serge Pauwels, who has set the fastest time at the split, comes home for provisional third at the finish, 55 seconds down on Cepecchi.
14:36 - Mario Cipollini, the Lion King, is at the finish in Polsa today. The 46 year old won a total of 42 stages on the Giro d'Italia in his time - a record that will not be beaten for quite some time, perhaps never.
9.5km - Sky's Dario Cataldo has set the new best time at the first check: the Italian's split time is 21:24 - which is a full 43 seconds faster than Pauwels. He's going extremely well.
20.6km - New best time at the finish: Eros Capecchi comes home 13 seconds quicker than Cummings. The new target time is 46:55 from the Movistar man.
14:30 - Yesterday's stage winner Gio Visconti is down the ramp. He'll be an interesting one to watch today after his victories on the Galibier and in Vicenza. He's on a road bike with TT bars.
14:23 - Pirazzi was five minutes late to the start and actually started a few riders back than scheduled. He'll be fined and will lose time for that.
9.5km - We have a new fastest time at the first check at Brentonica: Belgian Serge Pauwels (OPQS) takes seven seconds off Steve Cummings' effort. Meanwhile, Movistar's Eros Capecchi is also going strong: he's just one second short of the British BMC rider at the split.
14:21 - Having already won four stages (including the last three on the bounce), Movistar will love to get a win today: it is the two year anniversary of the death of Xavi Tondo, who was killed in a freak training accident on 23rd May 2011. Movistar already have wins for Dowsett, Intxausti and Visconti (x2).
14:18 - The blue jersey Stefano Pirazzi is on course. The Bardiani Valvole rider leads the KOM standings with 79 points to Giovanni Visconti's 45 points. So attacking in the mountains, the Italian looks a safe bet for the blue jersey in Brescia.
14:18 - Garmin's Tom Danielson catches two riders in quick succession ahead of the 15km-to-go banner: Lampre's Simone Stortoni and Movistar's Fran Ventoso.
14:15 - Miguel Angel Rubiano rolls down the ramp. The Androni-Giocattoli rider was part of yesterday's break and so may be rather tired today.
14:14 - Cataldo has already caught GreenEdge's Jens Keukeleire, who started two riders in front of him. It looks like he's going well.
14:12 - Sky's Dario Cataldo is on course. He's a rider who could do well today. Ill during the first week in which he had to ride in support of Wiggins, the Italian will be able to ride his own race today and could surprise.
14:09 - Manuele Boaro tired over the second half the course. The Italian is currently third, 50 secs off the pace set by Cummings.
20.6km - Swedish youngster Tobias Ludvigsson (Argos Shimano), who has had an active Giro with numerous breaks, has set the second best time at the finish, 43 seconds down on Steve Cummings, the current leader. Jerome Pineau of OPQS is third, at 1:15.
14:07 - Cadel Evans will almost certainly be in the red jersey tonight because there are points up for grabs. He trails Cavendish by four points in the standings and there are 5pts available for 12th place today - so as long as Evans finishes 12th or above, he'll take on the Stelvio tomorrow in red. Unless, of course, Nibali cracks big time today and Evans takes the maglia rosa...
14:03 - The 2011 Vuelta winner Juan Jose Cobo has set the seventh best time at the finish, one second under two minutes off Cummings.
14:01 - Manuele Boaro is one of the few riders to be using a time trial handle bar set up and aerodynamic helmet today. We haven't seen many so far. The Italian is currently on the second climb and it will be interesting to see if he makes any in-roads into Cummings' target time. Boaro was second at the split, remember.
14:00 - Mark Cavendish, the red jersey, is currently in 44th position at the finish 5:26 down on compatriot Cummings. Cav picked up some points at the intermediate sprints yesterday but Cadel Evans's 10th place on the stage meant the Australian moved to within four points of the Omega Pharma-Quick Step sprinter in the points standings. It's going to be touch for Cav to win the red jersey that he lost by just one point last year...
13:57 - Filippo Pozzato's all smiles as he crosses the line. The Lampre rider is a popular figure in the area but his time was not a good one. Pozzato has been disappointing in this year's Giro - hardly featuring in any of the sprints or breaks.
13:54 - Interesting to note that few of the riders are using special time trial bikes - the course is so steep and with only one short downhill and flat drag, there is really no use in riding with the special time machines that we saw in the opening, flatter ITT.
9.5km - Manuele Boaro (Saxo-Tinkoff) has set the second best time at the first check, 16 seconds down on Cummings.
13:48 - At the moment the riders are leaving at one-minute intervals but the staggered starts will be increased to three minutes for the top 15 riders. The top five will roll down the ramp as follows: Niemiec 15:21, Scarponi 15:24, Uran 15:27, Evans 15:30, Nibali 15:33.
13:46 - Briton Steve Cummings won a stage in the Vuelta a Espana last year and rides for the BMC team of Australian veteran Cadel Evans, who will hope to pile the pressure on Vincenzo Nibali today. The big news overnight is that Evans has been given the nod ahead of American Tejay van Garderen as BMC's number one rider at the Tour de France next month, according to team president Jim Ochowicz. The 2011 champion is riding back into his best form and is on course for a podium in Brescia.
13:42 - Dutchman Thomas Dekker (Garmin-Sharp) has just set the second best time at the finish, 1:29 down on Cummings' benchmark.
13:41 - Britain's Alex Dowsett won the race's first time trial by 10 seconds over compatriot Bradley Wiggins, who has since left the race with illness. Over a considerably steeper parcours, Movistar's Dowsett could not repeat his winning ride today: he is currently in eight place at the finish, 2:48 down on the current leader Steve Cummings.
13:37 - The maglia rosa Vincenzo Nibali will be the last to roll down the ramp at Mori. The Italian from Astana will start his time trial at 15:33 UK time - so in just under two hours' time.
13:35 - The starting ramp for today's TT is in the Velodrome at Mori, which is a nice touch. The riders first complete a lap of the circuit before the first climb to Brentonico for a rise of 187m to 695m. The final climb is longer and steeper, with the finish at Polsa at 1205m.
13:30 - Cummings holds the best time at the first split at Brentonico too. His time of 22:14 is the current target after the first ascent at 9.5km, with Italian Gianluca Brambilla (OPQS) 19 seconds down in second place.
13:25 - We pick up our live coverage of the time trial with Britain's Steve Cummings in the provisional lead. The BMC rider set a time of 47:08 for the 20.6km course and leads Spaniard Miguel Minguel of Euskaltel by 1:47.
13:20 - It's a sunny day in northern Italy and the temperature is 23 degrees Celsius. There is an intermediate time check at the town of Brentonico at 9.5km.
13:15 - While not a high mountain time trial in the mould of Alpe d'Huez, today's test could see some significant changes in the top ten. The 20.6km course can be split into three distinct phases: an opening section of wide, newly surfaced roads with an average gradient of 6%; a short and gentle descent into Brento with a false flat for 3km; the final 7km to the finish, with constant climbing and a steeper average gradient of almost 8%.
13:10 - Maglia rosa Vincenzo Nibali (Astana) finished safely in the main pack yesterday to retain his race lead by 1:26 over Cadel Evans (BMC) and 2:46 over Rigoberto Uran (Team Sky) ahead of today's decisive 20.6km uphill time trial. Lampre pair Michele Scarponi and Przemyslaw Niemiec are fourth and fifth at 3:53 and 4:13 respectively.
13:05 - Yesterday. Italy's Giovanni Visconti took a second - and his Movistar team's fourth - triumph on the Giro after an audacious solo attack on the only climb of day near the finish in Vicenza. Visconti attacked the main pack on the punchy Cat.4 ascent of Crosara 20 kilometres from the finish of the otherwise largely pan-flat 218km stage from Caravaggio. The 30-year-old, who won on the Galibier three days earlier, held on to win by 19 seconds.
13:00 - Welcome to LIVE coverage of stage 18 of the Giro d'Italia - a 20.6km uphill time trial from Mori to Polsa.