And it's over!!! What a display from Chelsea. They are through to the Champions League final!! An astonishing game which will live long in the memory.
Chelsea are just seconds away now.
Utterly, utterly astonishing. Barca are exposed on the break as Torres bursts through, rounds Valdes and slots into an empty net. You could not make it up.
GOAL FOR CHELSEA!!! TORRES SCORES!!!!
Puyol heads over. Three minutes of added time to be played. 180 seconds. Count them, one by one.
Another good save from Cech as he turns away Mascherano's driven effort.
Meireles is booked after bringing down Mascherano and will also miss the final now, should Chelsea go through,
Another Barca move comes to nothing as Messi loses the ball on the edge of the box. Two minutes and stoppage time. Time to chew off what is left of your nails.
Barcelona waste a corner as Keita gets his angles all wrong in the box.
Messi bursts forward and then attempts to feed Sanchez, but Cech is out to gather.
Messi is crowded out after Dani Alves' cross is headed away. Chelsea five minutes away from the final now.
MESSI HITS THE POST!!! So close for Barcelona, but the Argentina ace's effort from the edge of the box strikes the foot of Cech's upright and away to safety.
Sanchez finds the back of the net, but the flag was already up for offside against Dani Alves. Tight call.
Barca have had 72 per cent of the possession, but just cannot find a way through.
Drogba makes way for Fernando Torres.
Great play by Mikel as he goes shoulder-to-shoulder with Tello in the box and wins the battle of strength.
Handball by Drogba on the halfway line, but the referee waves play on. Another Barca attack comes to nothing.
Busquets fires over the bar after Iniesta's ball into the box is headed down by Dani Alves. Another chance missed, and a few more seconds tick by.
Chelsea have the chance to break but Kalou's ball towards Ramires is lacking in direction and Barca have possession once again.
Fabregas makes way for Seydou Keita as Barcelona make their final change.
The minutes are ticking away, and still Chelsea are standing firm.
Another great block in defence, this time Mikel to deny Iniesta.
Lampard swiftly follows him into the book for up-ending Fabregas.
Messi's less-than memorable night continues as he is booked for pulling back Lampard.
Overhead clearance by Ramires after another lengthy spell of Barcelona passing. But the pressure is still on.
Drogba limping around and getting no sympathy from the referee.
Half a chance for Chelsea with Kalou in space, but Valdes is out to smother and the opportunity is gone.
Change for Barcelona, with Tello coming on for Cuenca.
The corner comes to nothing, but the respite is only momentary and Barca are back in possession and probing for a way through.
Barcelona are camped on the edge of the Chelsea box and Ramires has to concede a corner from Dani Alves' cross.
Glorious chance for Chelsea as Ivanovic has a free header from a corner, but cannot get it on target. Could be a key moment.
Xavi attempts a cross-field ball to Dani Alves, but overhits it and Cech has another goal-kick to launch downfield.
Great save from Cech as he comes out quickly to smother Cuenca's shot after the youngster had been found in space on the far side of the box.
Cuenca tricks his way into space and fires over a low cross which Ivanovic does well to clear from close to his own goal.
Cech goes into the book for time-wasting as he prepares to take a goal kick.
Juan Mata makes way for Salomon Kalou.
Audacious attempt from Drogba as he wriggles free in his own half before shooting from fully 50 yards out, but Valdes is able to get back and save.
Barcelona continue to probe and Dani Alves' cross to the far post is headed narrowly wide by Alexis Sanchez.
Handbags on the edge of the Chelsea penalty area as Lampard and Fabregas get embroiled in a minor spat.
Couple of bookings, with Ivanovic cautioned which will rule him out of the final, while Iniesta has also been shown the yellow card.
Simply astonishing. Messi, who has never scored against Chelsea, blasts his kick against the bar and it bounces away to safety. Huge let-off for the Blues.
Messi places the ball on the spot, but he lashes his kick against the face of the bar!
PENALTY TO BARCELONA!!! DROGBA BRINGS DOWN FABREGAS.
Barca are inches away from going back in front as Ivanovic reacts well to block Iniesta's goal-bound shot.
Barca get us under way against the 10 men of Chelsea who are set for a real backs-to-the-wall spell.
And we're back for the second half. Hold on to your hats.
The referee blows for half-time. An astonishing 45 minutes of football. Barcelona looked to be home and hosed at 2-0 up and with Chelsea down to 10 men after John Terry's red card, but Ramires now has the Blues on top courtesy of his delightful away goal.
Brilliant, brilliant goal from Ramires as he bursts clear and produces a simply stunning first-time chip over Valdes to give Chelsea a crucial away goal, which would see them through if the score stays the same.
GOAL FOR CHELSEA!!! RAMIRES!!!
Ramires is booked in the aftermath and will miss the final should Chelsea progress.
Just as Chelsea were looking to hang on to half-time, they are cut open as Messi feeds Iniesta and he draws Cech off his line before slotting into the bottom corner.
GOAL FOR BARCELONA!!! INIESTA!!!
All change at the back for the Blues, with Bosingwa now in at centre-back alongside Ivanovic and Ramires moving to right-back.
What on earth was Terry thinking? Totally needless red card for a cheap and blatant knee into the back of Alexis Sanchez. Reports are that the assistant referee alerted Cakir to the incident.
Big call from referee Cuneyt Cakir as he brandishes a red card to dismiss the Chelsea captain, who gave Alexis Sanchez a needless knee from behind on the edge of the area. Awful few minutes for the Blues.
RED CARD FOR CHELSEA!!! JOHN TERRY SENT OFF!!!
Barcelona finally find a way through as Drogba half clears a corner, but Dani Alves feeds Fabregas who cross for Busquets to tap home.
GOAL FOR BARCELONA!!! Busquets scores!!!
Fabregas attempts to feed Iniesta down the left channel, but the midfielder just overhits his pass and it goes out for a goalkick.
John Obi Mikel goes into the book for a late challenge on Alexis Sanchez.
Drogba's flick from Cech's launched clearance causes panic and Valdes slices it away with Mata sniffing.
Another corner for Barca as Xavi's shot deflects behind. The home side take it short and Xavi fires in another attempt which skids wide of Cech's goal.
The pattern of the half continues, Barcelona possession, passing and the Blues resolute at the back. Cech has been superb when called on tonight.
Drogba heads clear with Puyol closing in.
Iniesta and Fabregas combine, but Chelsea stand firm again. Bosingwa then gives the ball away and Barca have a corner.
Barca forced into a defensive change too, with Pique making way and Dani Alves coming on.
Another huge clearance from Cech releases Drogba, who gets away from Pique but can only find the side-netting from a tight angle. Half a chance for the Blues.
Rare effort on goal from Chelsea as Drogba hooks the ball over his shoulder and towards goal from the edge of the box, but his effort lacks power and is off target.
Mascherano tries his luck from long range but his speculative effort goes safely over Cech's bar. The goalkeeper, who has been excellent so far, looked like he had that covered.
Cuenca's cross finds Fabregas, but the former Arsenal man can only find the side-netting.
Pique is back on the field, Barca are back on the attack and Cech saves brilliantly from Messi with his feet.
Pique is back on his feet and off the field getting checked over. He looks a bit on the groggy side.
Horrible collision between Pique and Valdes, with the centre-back looking like he could have been knocked out cold. Medical teams are on and he is now sitting up, thankfully.
Cech's monster clearance is fisted away by Valdes, who takes out Pique and Drogba in the process. All three are down on the turf.
Ivanovic has slotted in alongside Terry in the centre of defence, with Bosingwa at right-back.
More resolute defending from Chelsea and they earn a throw in Barca's half after Frank Lampard is challenged by Pique. Mata then fires a ball into the box, but it is too easy for Valdes.
Cahill has to make way, with Bosingwa coming on. Big blow for the centre-back and for Chelsea.
Barcelona are camped on the edge of the Chelsea box, with neat inter-passing finally ended when Cuenca's cross is hacked away by Ramires.
Cole clears from under his own bar as Barcelona pour forward.
Bosingwa was ready to come on, with fourth offical having board ready, but Cahill has signalled he wants to continue.
More good work from Cech as he races from his line to gather a high ball into the box from Messi.
Not looking good for Cahill at all, Bosingwa is getting ready to join the fray as play goes on.
Only defensive option among Chelsea subs is Bosingwa. Essien, at a push.
Worry for Chelsea here as Gary Cahill is down in the area after tracking back to tackle Sanchez.
Low cross from Cuenca after good work from Xavi is cleared away by Gary Cahill.
Side-netting from Messi as he passes up a great chance to level the scores after swift interchange of passes with Sanchez. Should have made Cech work there.
First touch for Petr Cech as he comes off his line to gather a through ball from Xavi which was just too long for Alexis Sanchez.
First touch for Messi, and he gives it away. The great man is human.
Early attack from Chelsea as Cole breaks down the left and looks to find Ramires, but Valdes is quickly off his line to gather. Good start from the visitors.
Chelsea, wearing white, get us started.
Pre-match formalities completed, handshakes done, we're about to get under way.
Good job the mascot with Mascherano wasn't stood with Messi, he would have been taller than the Barca ace...
Here we go, the two teams are making their way out onto the playing surface for what promises to be a memorable 90 minutes, with the prospect of extra time and penalties also in the background.
Teams are in the tunnel and Camp Nou is in full voice. Amazing stadium and amazing noise.
Jason writes: "Managed to find a TV showing the match in the middle of the Indian Ocean (Mauritius)! Come on you true Blue boyzzzz! Terry, Drog, Lamps & Cech will be sooo hungry, it has to be our night!! One goal for us, and it will be a mighty task for the Catalans, GO CHELSEA!!!" Watching in Mauritius? That's the life.
James from Colchester adds: "Looking for Barca to win this one 3-1, Sanchez, Messi and a late header from from Puyol to score for the mighty Barcelona and Mata to score for Chelsea."
@technaught writes: "Following you from California! 3-2 to Barca. Barca early, Chelsea gets one 50+, Barca Penalty 60+ Cesc to Messi seals it late." Very detailed...
OK, might as well stick my neck on the line too. I'm going for a 2-0 victory for Barcelona to see them through to the final. Chelsea fans - you'll be pleased to know I'm appalling at predicting correct scores.
Di Matteo: "We need a top performance tonight."
Roberto di Matteo tells Sky Sports he believes Chelsea will have to score tonight if they are to progress.
Quick huddle from the Barca squad after their warm-up and they leave the field for some final words of wisdom from Pep Guardiola in the sanctuary of the dressing room.
David O'Connell says: "If Chelsea manage to get a goal before Barca then I really cannot see a way back for Barca. However if Barca score first then we will see a flowing game with Barca winning out with great football."
Carles Puyol and Javier Mascherano are walking the same disciplinary tightrope for Barcelona.
Branislav Ivanovic, Ashley Cole, Ramires and Raul Meireles have all been booked previously in the Champions League and would miss the final if they receive another caution tonight.
The big news in the Barcelona squad is that Dani Alves only makes the substitutes' bench as coach Pep Guardiola makes two changes from the side that lost in London, with Gerard Pique and Isaac Cuenca drafted in.
Full team news is earlier in the commentary, but for those who missed it, these are the headlines: Didier Drogba returns from injury as Chelsea stick with their first-leg side. The Blues name the same starting XI that won 1-0 at Stamford Bridge and are boosted by Drogba's recovery from a knee injury that saw him miss Saturday's clash with Arsenal.
Damon from Selby writes: "This is an unbiased comments site you have going here???? Anybody that saw Chelsea perform with 11 men behind the ball and one attack all night can't really think them winning is going to be a good advert for football if the 2nd legs like the first? Did Didier recover from his fractured cheek bone in his left buttock from the last game after his diving and rolling around?" I'm guessing he's not a Blues fan....
And @ants34 says: "I am a #cfc fan but fear we can't hold off the Catalan giants again! Hope we do though."
Gordon Phillips says: "I've got good friends who are Chelsea supporters, so I hope they do well for them. But the football loving part of me hopes Barcelona slaughter them. I think teams that play football deserve to win."
Donna Marsden from Workington writes: "Tonight's game is going to be intense, but I have faith in my Barça boys and I know they will do us all proud and beat Chelsea! I'm predicting an end score of 3-1 to Barça. Fàbregas to score one of those at least!!"
Chelsea players going through their warm-up routines out on the pitch at Camp Nou - kick-off is just half an hour away now....
Ragel in Jamaica writes: "I believe Chelsea will come out victorious once again because they have the determination to defend their goal at all cost, and they came out with a game plan and stuck to it and if they stick to it again barca is going down."
Final word from Opta: Chelsea are the team Lionel Messi has played the most against in the Champions League without scoring: seven games, zero goals.
And another stat from Opta: In the first leg Barca had six times as many attempts on goal (24-4) and shots on target (6-1) as Chelsea.
More from Opta: Pep Guardiola's men have failed to score in two of their last three Champions League games, prior to that they had been on a run of 29 games without being shut out by their opponents.
Couple of interesting stats from Opta: Chelsea are the only side who have faced Barca more than four times in the Champions League who can boast a positive head-to-head record against the Catalans (W4, D4, L3).
A few words from our friends at Sky Bet: Despite trailing by a goal from the first leg and losing El Clasico at the weekend Barcelona are 2/5 to qualify for the final with the Blues a 7/4 shot. On the night it's 2/9 for a Barca win, 8/1 for Chelsea and 13/2 for the draw. We offer 12/1 for Didier Drogba to net the first goal to follow up his winner in the first leg at Stamford Bridge or 9/4 for Lionel Messi to strike first.
Tactical analysis from Justin as he reckons: "I am looking at a 3-3-4 Barcelona with Daniel Alves on the bench. Chelsea's line up is to counter the fast wings. But Barcelona is going to be focusing on attacks in the middle. With the relatively slower players in the middle, I am very nervous for Chelsea."
Leighton Brady writes: "Irishman watching the game on my laptop in upstate NY. I'm a Man U fan but am really rooting for Chelsea. I always rather have the English teams do better. (except the Pool). Anyway should be a cracking game of all out attack from the Spaniards and we'll have to see how well the Blues can hold them, but I fear not and am predicting a 3-0 Barca score. But I really hope Chelsea pull it off and meet the Germans in the final."
Tonight's referee is Cuneyt Cakir from Turkey. Let's hope he's not the talking point after the match.
More from Twitter as @jackkemptonn writes: "I'm a chelsea fan and if chelsea defend well, they will win tonight! Always 10behind the ball! Come on you blues!"
And @iamrperry says: "Watching it in 3D at home with friends and beer. All Chelsea. Massive game tonight. 2-1 Barca on the night. C'mon the Chels!!"
@AndyJohnGreen writes: "First CFC showed MCFC how to beat Napoli then we showed MUFC how to beat Benfica, now lets show the world how to beat barca!!"
Sean Doran is watching the game in Steamboat Springs, Colorado and says: "I think its going to be Chelsea's night with them playing a brand of football that worked in the 1st leg, defending for their lives but I really do think Chelsea are going to cause the upset."
James from Orpington writes: "I am really nervous about tonight's game. If we went through it would be AMAZING. My prediction 3-2 Barca with the mighty Blues going to Munich on away goals."
Chelsea subs: Turnbull, Bosingwa, Essien, Malouda, Sturridge, Kalou, Torres.
Barcelona subs: Pinto, Alves, Adriano, Thiago, Keita, Pedro, Tello.
Chelsea: Cech, Ivanovic, Cahill, Terry, Cole, Meireles, Mikel, Lampard, Ramires, Drogba, Mata.
Barcelona: Valdes, Puyol, Mascherano, Pique, Sergio, Xavi, Iniesta, Cesc, Alexis, Messi, Cuenca.
Let me know where you're following the game from, who you're supporting, and how you see it panning out. Who will be the key players? Can Chelsea shut out Messi again? Who should Di Matteo start with up front? How many times will Didier Drogba fall over?
To have your say on tonight's contest then drop me a line to email@example.com or via Twitter @skysportsrobp and I'll publish a selection of the best prior to kick-off.
The eyes of the world will be focused on tonight's contest, with all Blues fans hoping that their side can repeat the heroics of last week's first leg at Stamford Bridge and again repel the attacking waves from Barcelona.
The waiting is almost over and there is only a little over an hour until kick-off with Chelsea holding a slender, yet crucial, 1-0 advantage from the first leg.
Good evening and welcome to our live and interactive commentary on tonight's UEFA Champions League semi-final second leg from Camp Nou.