Welcome back, the Beast of the Blues
Spaniard the driving force behind one of the Blues' best displays this season
(Ivan Marcano 12-og, Willian 52)
For one night only, the Chelsea of old returned with a vengeance.
Jose Mourinho's players managed to pull back the guillotine hurtling towards their beleaguered manager's neck.
How long they are able, or willing to maintain its grip remains to be seen.
Roman Abramovich's delight in high-fiving supporters in the directors' box was the closest thing to a sign of approval for Mourinho from Chelsea's billionaire owner.
It signalled some much-needed breathing space, until mid-February at least.
A point would have been enough to secure Chelsea's place in the knockout stages of the Champions League, but even that came without any degree of certainty in a year which has lurched from the lofty heights of success to the doldrums of despair in little more than five months.
Mourinho had conceded that his side are, understandably, considered to be among the "weaker" sides at the competition's knockout stage.
Few witnessing their safe passage as Group G winners yesterday morning (Singapore time) would have agreed with that assertion.
Carefree yet comfortable; this was Chelsea at their best.
An inability to replicate their continental exploits on the home front continues to defy comprehension.
In the English Premier League, a previously joyful coronation has deteriorated into an Annus Horribilis.
Europe, however, has provided escapism; a platform on which Chelsea's players have been allowed to cast off the shackles of their pitiful title defence and play with relative freedom.
Baris Simsek, the Turkish construction engineer-turned-match official, will be lauded for deeming that Ivan Marcano's own goal had crossed the line.
But Diego Costa's harassing and hounding, two traits sorely lacking from the Chelsea striker this season, was their driving force.
Such was the desperation to coax the best back out of Costa that Mourinho had held one-to-one tactical sessions with his profligate front-man.
The end product was in keeping with Stamford Bridge turning back the clock.
Porto were condemned to the Europa League because their defence could not get the better of him.
Even Iker Casillas lost his head when confronted by Costa's trademark over-reaching foot.
With the Spain international back to his menacing best, the goals finally returned.
In this vein of form, they will soon belong to him in his own right.
Fighting the world is what Costa does best.
His incendiary traits are indisputably Chelsea's greatest weapon.
Yet he has spent most of this season confronting the enemy within.
That is why this glimmer of hope could prove in vain when Chelsea travel to the King Power Stadium on Tuesday morning.
He is not alone in that preoccupation.
Champions League hangovers have become synonymous with Mourinho's side this season, with defeat by Stoke City and a stalemate at Tottenham Hotspur both followed European bows.
In the current EPL climate, a repeat against table-toppers Leicester City cannot be discounted.
Nor can faltering at the first hurdle. The Portuguese's lowered ambition of Europa League qualification has been banished for another two months at least.
Fates in the Round of 16 draw, however, threaten to place it firmly back on the agenda.
That in itself continues to cloud Chelsea's season in uncertainty.
The bib (incident) is in the past. I made a mistake, but my relationship with Mourinho is amazing, we get on really well.
— Diego Costa on throwing a bib at manager Jose Mourinho during Chelsea’s 0-0 draw with Spurs
His attitude was very good and his movement was much better. Goals are coming.
— Chelsea manager Jose Mourinho on striker Diego Costa
BY THE NUMBERS
Chelsea have won 36 of their last 37 home matches in the group stage of the Champions League.