Chelsea produced the kind of "perfect" performance Roberto Di Matteo had demanded tonight to inflict Barcelona's first Champions League defeat of the season and give themselves real hope of reaching the final.
The Blues once again proved the nemesis of the team feted by many as the greatest to play the game thanks to an amazing smash-and-grab display in the semi-final first leg at a jubilant Stamford Bridge.
Caretaker manager Roberto Di Matteo's plan paid off spectacularly, Didier Drogba scoring the winner to go some way to burying the demons of the sides' last meeting three years ago.
As well as being magnificent to a man in carrying out the instructions of Di Matteo - whose claim to be appointed manager on a full-time basis is becoming irresistible - Chelsea also enjoyed the kind of luck that deserted them in 2009 and which they have had in spades since the Italian took charge.
They may need plenty more at the Nou Camp on Tuesday to reach their second final after Barca missed a glut of chances after dominating possession from start to finish.
The pattern of the match was set the moment the visitors kicked off, Chelsea allowing them possession to a point and Raul Meireles leading the pressure behind Drogba.
From a defensive point of view, it largely worked, although the visitors should have taken one of the chances to have fallen their way.
Luck played a part in the first of them in the ninth minute, Alexis Sanchez chipping against the crossbar from Andres Iniesta's perfectly-timed pass.
The other two both fell to Cesc Fabregas courtesy of Lionel Messi, who was otherwise restricted to a quiet half.
The first was a sitter, Fabregas shanking his finish after Messi's burst and pass had set up Andres Iniesta for a shot Petr Cech parried.
Messi finally had the chance to build up a real head of steam two minutes before half-time, Fabregas this time producing a delightful dink which was only kept out by Ashley Cole's clearance off the line.
Otherwise Chelsea had plenty to give them hope from what little ball they had.
The benefit of going long was quickly demonstrated when only a heavy touch prevented Drogba capitalising on Cech's clearance.
Drogba, who got away with overstepping the mark when he trod on Sergio Busquets' foot, also failed to make the most of a one-on-one with Carles Puyol.
Long throws predictably unsettled Barca, too, and Gary Cahill almost took advantage of the first of them.
Chelsea did tread a fine line discipline-wise, with Meireles lucky not to pick up a booking that would see him suspended for the second leg.
"Same old Barca, always cheating," chanted the home fans whenever a Barca player went down.
They were in good spirits despite the deluge, which may have played a part in Drogba scoring with the final kick of the first half.
Barca were caught upfield and Frank Lampard's ball over the top sent Ramires rampaging forward, the Brazilian's cross picking out Drogba.
Victor Valdes should have saved the scuffed finish but could only help it into the net.
Barca were even more dominant after the restart, Cech parrying Adriano's curler before Sanchez missed another gilt-edge chance when he stabbed Fabregas' scooped pass wide from six yards.
Otherwise they were being kept at bay by a world-class defensive display led by Cahill and John Terry, who were almost single-handedly keeping Messi at bay.
Pep Guardiola sent on Pedro for Sanchez with 24 minutes remaining, with Barca becoming increasingly frustrated, not least with perceived play-acting from Drogba, who got an earful from Puyol.
There was finally a booking when Ramires tripped Messi in full flight, Pedro quickly following for a similar offence on Cole.
Busquets was also cautioned for scything down Ramires after Juan Mata was withdrawn for Salomon Kalou.
Fabregas left the field to a chorus of boos for Thiago Alcantara as Chelsea began to drop deeper and deeper, as they had done three years earlier.
Barca laid siege to the Blues goal and Cech produced a magnificent save three minutes' from time when Puyol glanced Messi's free-kick towards the corner.
And, in stoppage-time, the visitors saved their worst finish until last, Busquets skying high over the crossbar after Pedro's effort had hit the post.