Didier Drogba's brilliant winner saw Chelsea take a giant stride toward the Champions League knockout stage and defeat holders Barcelona.
Drogba struck on the turn seconds after half-time to give Jose Mourinho's side a thoroughly deserved win and make it three straight victories in the group.
Chelsea were without keepers Petr Cech and Carlo Cudicini through injury, but third-choice Hilario was faultless.
And Drogba and Andriy Shevchenko wasted chances to double Chelsea's lead.
With Cech out with a fractured skull and Cudicini also missing because of concussion, it was feared Barcelona may take advantage, but they were kept at arm's length by Chelsea, with Michael Essien outstanding.
Barcelona carved out the first serious chance after 13 minutes when a pass from Deco set up Gianluca Zambrotta, but he blazed wide.
DEBATE
But Chelsea responded three minutes later, and it took a brilliant piece of last-ditch defending from Rafael Marquez to halt Andriy Shevchenko when he closed in on Drogba's shot as it ran loose in the box.
Hilario distinguished himself in the opening half, saving well from Lionel Messi and then Xavi after a superb passing move.
But Mourinho's side were always a threat, and Michael Ballack should have done better than head straight at Victor Valdes from Frank Lampard's corner a minute before half-time.
Chelsea broke the deadlock seconds after the break with a stunning strike from in-form Drogba.
He initially appeared to miscontrol Ashley Cole's pass, but recovered and swivelled to lash a 20-yard finish with his right foot past Valdes.
It was a goal the bore a remarkable similarity to his winner against Liverpool at Stamford Bridge earlier this season
Drogba's strike partner Shevchenko was, in contrast, still struggling in front of goal.
And he wasted an opportunity to extend Chelsea's lead after 54 minutes when he shot wide from 10 yards after being played into space by Lampard.
Chelsea needed the security of a second goal to guard against a potential moment of magic from Ronaldinho.
But they missed another chance to push themselves out of reach when Drogba shot straight at Valdes with only the keeper to beat from close range.
Shevchenko had endured another night of frustration, and it was no surprise when he was replaced with Arjen Robben with 15 minutes left.
Barcelona were enjoying plenty of possession, but chances were at a premium as Chelsea defended with typical resolution.
Hilario was sound, and when Xavi found Lionel Messi in the box he headed off target.
And he brought cheers from the crowd two minutes from time when he plunged low to save from Deco.
It was their final chance and Chelsea were able to celebrate a victory of real significance.
Chelsea: Hilario, Boulahrouz, Ricardo Carvalho, Terry, Ashley Cole, Ballack, Lampard, Makelele, Essien, Shevchenko (Robben 76), Drogba (Kalou 90).
Subs Not Used: Makaba-Makalamby, Joe Cole, Geremi, Bridge, Paulo Ferreira.
Booked: Lampard.
Goals: Drogba 46.
Barcelona: Valdes, Marquez, Puyol (Oleguer 74), Zambrotta, Van Bronckhorst (Iniesta 56), Messi, Deco, Xavi, Edmilson, Gudjohnsen (Giuly 60), Ronaldinho.
Subs Not Used: Jorquera, Motta, Thuram, Saviola.
Booked: Van Bronckhorst, Xavi, Deco.
Att: 45,999
Ref: Frank De Bleeckere (Belgium).