The Spanish giants go into the two-legged tie as heavy favourites as they look to become the first team to win consecutive Champions League titles.
However, Roberto Di Matteo's Blues are a much improved outfit in recent weeks and will be hopeful of adding a European final to their FA Cup final date at Wembley.
All eyes will be on Barca forward Lionel Messi. The Argentine has scored 63 times in all competitions this season and promises to be the Catalan club's biggest threat.
For the hosts, Didier Drogba is preferred to Fernando Torres up front after his impressive performance in their 5-1 victory over Tottenham Hotspur on Sunday.
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FULL-TIME: This wasn't in the script, but against the odds Chelsea have pulled off a surprise first-leg win over the European champions. Didier Drogba's goal gives the Blues a 1-0 advantage heading into the second-leg tie at the Nou Camp and, what is equally important, Chelsea's valiant defending prevented the Catalan club netting a vital away goal. Barcelona were dominant throughout and had the chances to match their superior possession, but full credit to the hosts, who were organised and stubborn at the back.
It was a great victory for Roberto Di Matteo's side but they'll still be considered underdogs to progress when they travel to Spain. Thanks for joining Sports Mole tonight and be sure to check back for live coverage of the second leg. You can read our full match report on the contest here.
FULL-TIME: Chelsea 1-0 Barcelona
90 min: Just as we were saying they didn't look like scoring, Barca come as close as they have all game. Messi, who has had a greater influence on the game as it has progressed, plays the ball into Busquets and then collects it back via the Spaniard's clever back-heel. John Terry comes across to dispossess the Argentine but his slide tackle ends up at the feet of Pedro, whose shot seems destined for the bottom corner. However, Chelsea's luck is in as it rebounds back off the post and with almost the last kick of the game, Busquets sends the follow-up effort high and wide.
90 min: Barca hit the post!
90 min: We are in Andreas Iniesta territory now, but there is no clear sign of Barcelona levelling the game.
90 min: We are now entering the first of three minutes of stoppage time. Can Chelsea hang on?
88 min: Somewhere in all of that action Jose Bosingwa has replaced Ramires for Chelsea.
86 min: Good save from Cech! Barca come close to finding an equaliser and that precious away goal. Messi floats a free kick into the area and Puyol stoops low to flick the ball goalwards, but Cech dives across to tip the ball wide.
86 min: Here is a rare sight. Xavi is taken off by Guardiola as Isaac Cuenca comes on for the closing moments.
85 min: Drogba joins Ramires in the book for Chelsea for a foul on Messi.
84 min: The home fans are nearly in dreamland as Kalou almost adds a second. Barca fail to deal with Drogba competing for a long punt forward and the ball drops to Kalou, who can't get over the ball and sends his shot over.
83 min: Chelsea have everyone, including Didier Drogba, camped in their own half as they await a Barca barrage in the latter stages.
80 min: Messi is dropping deeper and deeper to collect the ball. You just know that he'll have an impact on the tie at some stage, but will it be in the remaining 10 minutes tonight?
78 min: Guardiola makes another substitution in an attempt to find an away goal. Young Spanish international Thiago is on in place of compatriot Fabregas, who was guilty of wasting a great chance in the first half.
75 min: Make that 2-1 in bookings as Sergio Busquets is cautioned for hacking down Ramires as the Brazilian attempted to break down the Chelsea left.
72 min: Roberto Di Matteo is preparing his first change of the night, with Salamon Kalou stripped and ready to go. The Ivorian replaces Juan Mata.
70 min: We are now one apiece in terms of yellow cards as Pedro follows Ramires into the referee's book just minutes after his introduction.
69 min: Again wasteful from Barca as Xavi strikes powerfully over the bar, with the ball never threatening Cech's goal.
68 min: Another free kick for the Catalan outfit in nearly an identical position. Ramires flies into Messi from behind and is shown a yellow card.
66 min: Sure enough, Guardiola has made his move, bringing Pedro on for Alexis Sanchez in a like-for-like replacement on the right flank.
65 min: Messi is getting more and more involved in the game, which is an ominous sign for the Blues. This time Chelsea gift him the ball and he dribbles past a couple of players, getting a slice of fortune on his way, but his shot is blocked again - this time by Terry.
64 min: Straight into the wall. Will Pepe Guardiola start looking at his bench soon? Pedro and Cuenca are possible options...
63 min: The visitors have a free kick in a dangerous position on the edge of the area. Messi is over it...
61 min: It really is all Barcelona here but they, and Messi, are frustrated again. The forward runs through, beats two men and looks to have the beating of Cahill too, but the Chelsea defender recovers and wins the ball well.
56 min: Great chance for Barca! Barca's two summer signings combine as Sanchez plays a delightful give and go with Fabregas, whose chipped through ball opens up the Chelsea defence. Sanchez is in on goal six yards out but can't get the ball out of his feet and somehow pokes it wide. Credit to Ashley Cole, who just did enough to pressurise the Barca man.
54 min: Chelsea are defending stubbornly here and you feel they'll have to if they are to retain their advantage. Firstly Cahill blocks well from Messi and then pinches the ball away from Sanchez before the forward can shoot at goal.
52 min: Frank Lampard's dangerous corner evades all in the box as a stretching Gary Cahill just fails to make contact at the back post.
50 min: Cech is called into action for the first time since the break as Adriano cuts in from the left and tries to bend a shot into the far corner, but the Chelsea stopper palms the ball away.
49 min: As it was in the first period, it is all Barca in the early stages of the second half. A two-minute spell of possession leads to Iniesta's shot being deflected behind for a corner, which came to nothing.
46 min: The action has resumed here at a rainy Stamford Bridge, where Chelsea lead Barcelona 1-0.
HALF-TIME: Not many people saw this coming, maybe not even Chelsea, who have largely been dominated in the opening 45 minutes. They've worked hard and been organised in midfield, but rarely did they threaten the Barca goal and the visitors inevitably looked a danger at the other end. Still, they'll be delighted with this half-time scoreline.
45 min: With the last kick of the first half, Chelsea have taken the lead with their first real chance of the game and it's again Didier Drogba. Messi gives the ball away in the middle of the park and when Frank Lampard switches it to Ramires, the Blues have a two-on-two situation. The Brazilian runs into the box before sliding in Drogba, who had peeled off at the back post to strike home left-footed into the bottom corner.
45 min: GOAL!! Didier Drogba- Chelsea 1-0 Barcelona
45 min: Into first-half stoppage time here, with the fourth official indicating there will be around two minutes.
43 min: Off the line from Chelsea! Messi picks up the ball between the Blues midfield and defence and runs at Terry and Cahill before playing it through to Fabregas. Cech comes to meet the Spaniard, who lifts it over the Chelsea stopper but Ashley Cole is back to sweep the ball off the line.
41 min: A Barca corner is headed clear by Gary Cahill and with the ball looping in the air, Danny Alves's eyes light up but he sends his volley way over the bar.
39 min: Drogba has had a frustrating first half so far. He's spent more time either on the floor or in an offside position then he has influencing the game. It was around this time he found a moment of brilliance to open the scoring for Chelsea on Sunday. What they'd give for a repeat tonight.
35 min: Puyol appears to have some sort of injury problem. The Barca captain runs over to the touchline holding his wrist, but he is bandaged up quickly and takes his place back on the field.
31 min: Just seen a replay of that Iniesta penalty shout. It looks to be just inside the area and it is a tad clumsy from the England defender, but it would have been a soft decision had it been awarded.
30 min: Chelsea will be pleased to have survived the opening half-an-hour, but Barca's possession is starting to result in some decent chances. The hosts could really do with keeping the ball for a few minutes.
28 min: Messi has his first effort on goal and surprisingly it's a header. The Argentine meets a Sanchez cross from 12 yards but Cech gets across comfortably to save.
26 min: Cahill is again tested as this time Fabregas gets away from him just inside the box. The former Arsenal captain finds room for a shot but it is straight at Cech, who palms powerfully clear.
24 min: Perhaps half a penalty shout for the visitors as Gary Cahill appears to lean in on Iniesta. The tricky Spaniard twists and turns his way past the centre half with some clever footwork before being brought down under Cahill's challenge. Minimal contact and it could have been outside of the area. Good decision.
21 min: Chelsea have the opportunity to break from a Barca corner as Meireles and Mata attack down the left. The former tries to find a surging Branislav Ivanovic with a switch of play but the pass is off target.
17 min: Great chance for Barca! Messi weaves his magic for the first time, picking the ball up on the edge of the box before jinking through several Chelsea defenders. He lays the ball back to Iniesta, whose shot is parried by Cech and with most the goal to aim at, Cesc Fabregas scuffs his shot from eight yards.
14 min: A bad sign for the Blues as Didier Drogba goes down clutching his leg. You never know though with the Ivorian and sure enough, he is back on his feet seconds later.
10 min: At the other end, Chelsea's long throw causes problems in the Barca box and it looks for a second as if John Terry will have a tap in for 1-0. However, Daniel Alves clears the ball before the England skipper can reach it.
8 min: Barca hit the crossbar! In a flash Alexis Sanchez is through and the Chilean lobs Cech but the ball comes back off the crossbar. First real scare for Chelsea.
6 min: The home crowd gets excited momentarily as Drogba pokes the ball past Javier Mascherano and has the chance to run one-on-one at Carlos Puyol. The experienced Spaniard stands his ground though and guides the ball back to Victor Valdes.
4 min: Drogba appears to be in on goal courtesy of Cech's long punt forward but the Ivorian's touch is heavy and it comes to nothing. The Chelsea striker is called for a foul on Sergio Busquets moments later.
3 min: As you might have expected, Barca have had almost all of the ball in the opening minutes, but the first time Messi gets it he is shrugged aside by Ramires. That bodes well.
1 min: We're underway here at Stamford Bridge...