Two second-half goals from Maxi Lopez and Samuel Eto'o condemned Chelsea to a narrow first leg defeat against Barcelona in the Nou Camp stadium.

An own goal by Juliano Belletti had gifted the Barclays Premiership side a first-half lead but they failed to hold on to their advantage after the break and the game turned when striker Didier Drogba was cruelly sent off by Swedish referee Anders Frisk for a second bookable offence.

Substitute Maxi Lopez equalised with a right-foot drive in the 66th minute and then his shot was diverted in by Eto'o seven minutes later.

Mourinho had insisted it was "almost impossible" for Damien Duff to have taken any part in the game because he was in so much pain from the knee injury he collected in Sunday's FA Cup fifth round defeat by Newcastle that he could hardly walk.

But the winger made a mockery of Mourinho's claim as he sped on to Frank Lampard's 40-yard pass and sent over the low cross that Barcelona defender Belletti turned into his own net in the 33rd minute.

The goal arrived totally against the run of play with the Primera Liga leaders in full control in the opening half.

But Chelsea could have finished the opening 45 minutes two goals to the good had Drogba realised he had more time and space to finish off another wonderful through ball from Claude Makelele.

Predictably, against a team rated as favourites to lift the Champions League crown and seven points clear at the top of their domestic league, Chelsea began the first leg in a somewhat nervous fashion.

And it was hardly a surprise to anyone in the vast bowl that is the Nou Camp, that Barcelona contrived an opening after only three minutes.

Frank Lampard's distribution is normally unquestionable but his lack of accuracy allowed Samuel Eto'o to intercept the ball and slip Ronaldinho in the clear on the left flank.

But the Brazilian's shot whistled past Petr Cech's left-hand post as did another effort from Eto'o himself moments later as the hosts took full advantage of an edgy Chelsea defence.

The Londoners were further exposed in the 10th minute when their defence failed to deal adequately with a cross from Ludovic Giuly and Ronaldinho sent another right-foot shot wide of the target. Chelsea's midfield, with the exception of the hardworking Claude Makelele, displayed limited ambition to attack.

Instead, their tactical preference was to close down the space and time for the playmaking Deco and Giuly, along with Ronaldinho and Eto'o in attack.

The plan worked for much of the opening half with Barca restricted to few clear cut opportunities to open the scoring.

Two minutes after Belletti's error, Drogba could have put Chelsea two in front when Makelele's admirable through ball left the Ivory Coast striker in the clear.

But, with only goalkeeper Victor Valdes to beat, Drogba sent his shot wide of the right-hand post for a costly miss.

In the 38th minute, Chelsea began to take full advantage of a Barcelona side clearly reeling from Belleti's blunder and Joe Cole sent a 20-yard effort just too high as, for once, the Nou Camp fell silent.

The game erupted into controversy in the 55th minute when Anders Frisk red-carded Didier Drogba for what appeared to be nothing more than a 50-50 challenge for the ball with goalkeeper Victor Valdes.

Drogba had been booked in the first half for a foul on Rafael Marquez and, when the Chelsea striker and the goalkeeper went down as a result of the collision, the Swedish official produced a second yellow for the Ivory Coast man.

For the second time in as many games, the Londoners now found themselves down to 10 men, only this time they had 35 minutes to cope with a Barcelona attack given fresh hope by Chelsea's numerical handicap.

The Barca fans were also guilty of racist abuse towards Drogba with 'monkey' chants filling the air as he trudged slowly towards the visiting dugout.

In the 65th minute, Chelsea's luck held as substitute Andres Iniesta sent a left-foot shot inches wide of the post after Ricardo Carvalho had managed to block the first effort from Eto'o.

But a minute later the hosts were level when substitute Maxi Lopez finished off a three-man move involving Ronaldinho and Eto'o.

Lopez managed to squirm his way clear of William Gallas to fire an angled right-foot beyond Petr Cech in the Chelsea goal.

Worse was to come in the 73rd minute when Chelsea failed to cut out Maxi Lopez's drive from the right and Eto'o hit the matchwinner with a crisp drive from eight yards to give them a slender advantage to take to Stamford Bridge.

Teams:

Barcelona Valdes, Belletti (Gerard 85), Marquez, Puyol, Van Bronckhorst, Xavi, Deco, Albertini (Iniesta 57), Giuly (Maxi Lopez 64), Ronaldinho, Eto'o.

Subs Not Used: Jorquera, Sylvinho, Fernando, Abella Perez.

Goals: Maxi Lopez 66, Eto'o 73.

Chelsea Cech, Terry, Paulo Ferreira, Gallas, Ricardo Carvalho, Makelele, Lampard, Cole (Johnson 70), Duff (Gudjohnsen 76), Tiago (Smertin 90), Drogba.

Subs Not Used: Cudicini, Kezman, Geremi, Nuno Morais.

Sent Off: Drogba (56).

Booked: Drogba.

Goals: Belletti 33 og.

Att: 89,000

Ref: Anders Frisk (Sweden).