Andre Andre's opener for Porto late in the first half was quickly cancelled out by a superb Willian free-kick, but Maicon's 52nd-minute header proved to be the difference in this Group G clash played at a rip-roaring pace.

Porto were worthy winners, and Mourinho has now failed to win in three trips back to the Estadio do Dragao as Chelsea manager, following another 2-1 loss in 2004 and a 1-1 draw in 2007.

More importantly, Chelsea slip to third in Group G, a point behind Porto and Dynamo Kiev, who beat Maccabi Tel-Aviv 2-0 in Israel in the night's other game.

"It was a good performance with two ridiculous mistakes," said Mourinho.

"The second goal is a really bad mistake. We watch dozens of repetitions of Porto taking corners. I thought we were completely ready for that.

"But apart from that it was a balanced performance. The defenders played well and had no problems, but two ridiculous mistakes and we were punished."

Porto coach Julen Lopetegui said: "We are especially happy because of the attitude and mentality of the players. In the second half we wanted to keep attacking and creating and managed to win the game."

It was always going to be an emotional occasion for Mourinho as he went back to face the club he coached so successfully over a decade ago and led to Champions League glory in 2004.

However, Mourinho also needed a positive result from his side to divert attention away from their stalling Premier League form, and he acted decisively when it came to his team selection.

Eden Hazard and Nemanja Matic were both on the bench at kick-off in Portugal, while Oscar, Loic Remy and Radamel Falcao -- the former Porto striker -- were missing from the squad entirely.

Instead, John Obi Mikel, Ramires and Willian all started, as did Diego Costa, who is currently suspended in domestic competition.

Iker Casillas, who became a sworn enemy of Mourinho as the two fell out when working together at Real Madrid, started in goal for the hosts and made a record 152nd Champions League appearance.

And the Spaniard thwarted Chelsea twice in the opening exchanges, first turning behind a powerful shot from his international colleague Cesc Fabregas after good work by Costa. Then, Casillas rushed out to save from another compatriot, Pedro Rodriguez, who had been played in by Willian.

Meanwhile, Porto's formidable attack, featuring the brawn of Vincent Aboubakar and the mesmerising skill of Yacine Brahimi, were only showing flashes of their potential.

- Instant reward -

But when Brahimi finally took on Chelsea right-back Branislav Ivanovic, who has endured a troubled start to the season, it brought instant reward in the 39th minute.

He jinked into the box and tried a shot which Asmir Begovic saved. Begovic could not, however, keep out the follow-up from Andre Andre.

The Dragao roared, but it was silenced on the stroke of half-time. Ramires won a free-kick just outside the box and Willian stepped up to curl a beauty past a motionless Casillas for his third goal in as many games.

Porto were stunned, but Chelsea were unable to build on that moment of Brazilian brilliance as the home side regained the lead just seven minutes after the restart, their captain Maicon stooping to head a Ruben Neves corner low past Begovic at his near post.

Costa was desperately unlucky not to equalise virtually from the restart with a superb strike from wide on the left that looked to be arrowing into the far corner of the net but crashed back off the woodwork.

Nevertheless, the second goal galvanised a youthful and energetic Porto front six and they threatened to run riot as Giannelli Imbula stung the palms of Begovic and Aboubakar was denied by a crucial last-ditch block.

Mourinho sent on Hazard and Matic, as well as Kenedy, but still Porto looked stronger. Indeed, they deserved to win by a greater margin, but Danilo's header from a Miguel Layun corner agonisingly came back off the far post.

André André

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