Didier Drogba swept the ball into the net late in the first half, and Chelsea managed to hang on.
With an inspired performance, the Blues beat Barcelona 1-0 Wednesday night in the first leg of their Champions League semifinal and set up a must-see second leg of the total-goals series in Spain next week.
Either Barcelona will move within a victory of becoming the first back-to-back winner in more than two decades, or Chelsea will have the opportunity to win Europe's top club title for the first time.
"Now they are favorites," Barcelona coach Pep Guardiola said. "1-0 is a good result for them. You can imagine them having 10 players behind the ball again."
Lionel Messi lost possession of the ball in midfield, and Frank Lampard passed to Ramires for a counterattack. Ramires crossed to Drogba, who scuffed his shot but still beat goalkeeper Victor Valdes in the second minute of first-half stoppage time for his 38th Champions League goal. It was Chelsea's only shot on target.
"It was almost perfect," Chelsea interim manager Roberto Di Matteo said. "When you play Barcelona, you have to do a lot of defending and they have all the possession. You have to limit their threat and be clinical when you get your chances. It's 50-50 now — there is still a second leg to be played away from home."
Barcelona outshot Chelsea 24-5 had 72 percent possession, with Alexis Sanchez hitting the crossbar in the ninth minute and Pedro Rodriguez striking a post in second-half injury time.
"Only the winners are remembered," Guardiola said when asked if his team had been "mugged."
It was the first Champions League loss in 14 months for Barcelona, seeking to become the first team to win consecutive titles since AC Milan in 1989-90. The Blaugrana are 43-3-11 in all competitions this season.
"It will go down as one of our best performances," said Chelsea captain John Terry, who has played with cracked ribs in recent weeks. "We had to be patient — we didn't touch the ball in the first 10 or 15 minutes. It was a tireless performance."
Just before Drogba scored, a shot by Cesc Fabregas was cleared off the goal line by Chelsea's Ashley Cole. Fabregas had fluffed a shot wide with much of the goal to shoot for in the 17th minute.
Chelsea defender Gary Cahill was outstanding alongside Terry to repeatedly deny Messi, who has 63 goals this season but failed to score for only the second time in his last 15 matches.
"This game is about putting the ball into the net," Guardiola said. "And it's the most difficult thing. Now the challenge is to create these chances again. Maybe we will have to be more adventurous, take more risks."
With a must-win "Clasico" against Real Madrid in the Spanish league to come on Saturday and then the return leg against Chelsea three days later, Barca has little time to regroup if it wants to reach the Champions League final for the third time in four years.
In the other semifinal, Bayern Munich has a 2-1 lead over Real Madrid heading into next Wednesday's second leg in Spain.
Just sixth in the Premier League, Chelsea is unbeaten in its last six games against Barcelona. In their previous meeting, in the second leg of the 2009 semifinals, Barcelona advanced on Andres Iniesta's goal in the third minute of second-half stoppage time. An apoplectic Drogba left the field screaming at referee Tom Henning Ovrebo, earning a three-game suspension.
Three years later, the 34-year-old Drogba was all smiles as he lapped up the acclaim of the home fans.
"We have learned and we have improved from three years ago because we didn't concede," Drogba said. "The result is a good one, and we will go there and try to score another goal."