FC Porto 2 Chelsea 1

Jose Mourinho used to exude calm authority in these parts but, as panic gripped his Chelsea team here, the Portuguese could only scowl helplessly from the fringes of his technical area. All the vulnerability which has undermined the defence of his side's domestic title was exposed here in European competition, Porto rampant too often as the visitors lost all semblance of composure. This team is lurching from one befuddled display to the next.

This was a horrible defeat, the narrow scoreline deceptive with those who had made up Chelsea's fragile rearguard likely to be haunted for some time by the memory of Yacine Brahimi and his Porto team-mates pouring through them at pace.

Even the manager's tweaking of his line-up failed to have much of an effect, a rejigged team just as prone here as his previous selection had been at Newcastle on Saturday. Kurt Zouma saw his shot drift agonisingly wide of an empty net with the last kick of the match, but a draw would have been an injustice. This was a Chelsea team too often overwhelmed.

If those unnamed “six players” whose attitude, desire and commitment so displeased Mourinho in the first half at Newcastle had hoped the manager would forgive and forget then his selection here must have come as a rude awakening.

Eden Hazard and Nemanja Matic, modern mainstays of this team, had been cast among the substitutes, alongside the increasingly underused John Terry. Oscar, Loic Rémy and Radamel Falcao, who would have had his own motivation to excel here as a former Porto player, had not even travelled to Portugal, despite apparently being fit and available.

This was not quite as radical a selection as André Villas-Boas’s in Naples or Roberto di Matteo’s in Turin, both of which ended up feeling more like suicide notes but it still felt like a statement.

It certainly demanded a reaction and there was an initial urgency to Chelsea. The visitors were driven forward by Ramires and Willian – rare positives from Tyneside whose cameos had salvaged a point – with Cesc Fàbregas and Pedro slippery at their side and Diego Costa, restored in the midst of his domestic suspension, a mobile, aggressive focal point for his team. The Premier League side had provided a real threat on their brisk counter-attacks up to the interval and might have led. As it transpired, they were grateful to retire level.

They had been denied an early advantage by Iker Casillas, making a record 152nd Champions League appearance and, despite all the pre-match claims to the contrary, surely eager to add to Mourinho’s recent anxiety. The pair’s falling out at Real Madrid had been the root of much of the turmoil that had raged behind the scenes at the Bernabéu during the latter days of the manager’s three-year spell in charge. Here the veteran was soon blocking Fàbregas’s near-post attempt, created after Costa had burst through Maxi Pereira’s weak challenge on the flank and cut back for his team-mate.

Moments later the striker was nodding inside for Willian to liberate Pedro into the area, only for Casillas to turn away his low shot. Yet, for all their industry going forward, indecision still gripped Chelsea's back line. It manifested itself in skewed defensive headers or nervy decisions. Vincent Aboubakar was a menace, stampeding through Zouma and Gary Cahill, although it was Branislav Ivanovic whose jittery form was exposed for the hosts' opener.

The Serb, such a pale shadow of his former self, allowed Brahimi to turn inside too easily and, with Pedro reluctant to challenge, the Algerian spat a shot at goal that Asmir Begovic pawed out unconvincingly with his right glove. The first to react was André André who crunched a volley through the goalkeeper’s attempt to recover and into the net.

So pepped were the home side by that reward that they might have muscled further ahead in the frantic exchanges that followed, only to be undone themselves as half-time approached. Danilo’s foul on Ramires earned Chelsea a free-kick just outside the Porto area, which Willian curled deliciously beyond a static Casillas to register a third goal in as many appearances.

The Portuguese had not conceded in any competition at the Dragão since mid-April, a sense of shock accompanying them off the turf after that last kick of the half, but any momentum Chelsea might have hoped to generate was checked by the break. In truth, there was too much vulnerability on show here ever to suggest they might exert proper control.

A set piece quickly restored Porto's lead after the break, Ivanovic again exposed by a lofted pass down the flank with Zouma relieved to concede the corner after the excellent Brahimi's quick feet had teased space from Fàbregas. Ruben Neves duly delivered to the near-post where Maicon had burst away from Ramires, the centre half guiding a neat header inside the post, with Begovic again slow to react. Costa promptly curled an attempt against the angle of post and bar but Mourinho's response was to thrust on Hazard for John Mikel Obi, his initial plan in disarray.

Yet the Belgian joined team-mates on the rack, Begovic somehow blocking from Brahimi and defenders desperately flinging themselves in the way of Giannelli Imbula’s effort as chaos reigned in the visitors’ box.

Danilo should have provided the third only to plant a header on to the post when free at Miguel Layun’s corner. The marking had long since disintegrated, Chelsea a side laced with anxiety and their deficiencies disturbingly clear. These are troubled times. (Guardian service)