José Mourinho had turned to the East stand as this contest lurched towards its conclusion and, arms aloft, beseeched the home support to whip up one last roar to haul the team over the line. Within seconds his gesture was repeated in celebration. Liverpool, one of the more eye-catching contenders in this season's title race, had been beaten to inject proper conviction into Chelsea's own challenge. The Portuguese's reaction betrayed the significance of the result.
The first chink of light has been spotted between the top three and the chasing pack, a three-point gap chiselled out between Mourinho's team and fourth-placed Everton to suggest a massed scramble towards the summit is thinning out. Liverpool, a point behind their Merseyside neighbours, will hope to come again and can draw real encouragement from their displays even in defeat at the Etihad and Stamford Bridge but those at the top will likewise hope they are shrugging themselves clear. "A big win, a big opponent, a big match," said Mourinho. It was the kind of contest to get the juices flowing.
In the end, perhaps inevitably, it was also laced with controversy. Brendan Rodgers had reason to denounce Samuel Eto'o's first-minute foul on Jordan Henderson, the striker raking his studs down his opponent's right shin and escaping a card of any sort from Howard Webb. Though Liverpool scored from the free-kick that followed, they would have been taking on 10 men for 89 minutes had the offence been properly penalised. Their other gripe centred, inevitably, on Luis Suárez as Eto'o appeared to shoulder barge him off the ball and inside the penalty area seven minutes from time. Rodgers and Mourinho, once apprentice and mentor in these surroundings, could only agree to disagree, though in the circumstances it was perhaps inevitable that Eto'o's contribution would ultimately be remembered for the winner.
Chelsea had their own non-award to bemoan, Lucas Leiva appearing to floor the live-wire Eden Hazard 11 minutes in, yet the revival of the old Mourinho versus Merseyside rivalry should not boil down to perceived oversights by the overworked referee. This was combustible, breathless and blisteringly competitive and therefore enthralling to behold.
While Liverpool seemed stretched by cruel successive away fixtures, Chelsea arguably mustered some of their finest attacking football of the campaign through that ferocious opening period. Their forays forward were slick and conducted at pace, Oscar and Willian rapid in pouring upfield while Hazard, the team's player of the moment, orchestrated it all.
The Belgian, watched here by his brother Thorgan in the stands, has been untouchable in recent weeks. He has learned from the error of his ways after missing a training session following a brief trip back to Lille to watch his former club – it did not help that he had mislaid his passport in France – and has been resurgent since. He started the move which created Chelsea's equaliser, shifting the ball from central midfield to Willian before Oscar took up possession and bolted into enemy territory. Liverpool defenders backed off, uncertain and panicked, with the Brazilian's intended pass for Eto'o rebounding from Mamadou Sakho and back across the edge of the area.
Hazard, his run unchecked, dispatched it first time, all whip and bend, with Simon Mignolet helpless and beaten. "The kid is changing," said Mourinho of the £32m signing he inherited. "Before he was a very talented player but was a bit … not lazy, but a kid enjoying football just in a funny way. Now he understands responsibilities and that football is not just about getting the ball and playing like he did when he was 13 or 14 in the street. There are other ingredients needed at this level."
That was his 10th goal in all competitions this season, a tally that has eased some of the pressure on Chelsea's blunt strikers, though this would eventually be decided by one of their number. David Luiz and César Azpilicueta combined for Oscar to gather, his initial touch appearing to strike Sakho's arm. The crowd's appeals for handball went ignored, the playmaker regathering and turning the centre-half to square for Eto'o, granted too much space by Martin Skrtel, to convert. Mignolet should have done better.
The festive period has been unforgiving for Liverpool. They sat top of the pile on Christmas Day, rightly satisfied by their campaign and with Suárez signed up to a new contract, and yet, after the first successive league defeats of Rodgers' tenure, now languish fifth and outside the Champions League places.
That is sobering enough, even without Sakho (hamstring) and Joe Allen (groin) now injured and surely absent for the foreseeable future. And yet, as Rodgers pointed out, there was still promise to be picked up from each of their defeats over the past week, whether in the bite to the attacks summoned by Suárez, Coutinho and Henderson or the excellence – that second goal aside – of Mignolet in denying Chelsea further reward.
They had led early, Coutinho delivering viciously towards the near post, where Suárez and Branislav Ivanovic – those familiar foes from Anfield in April – tumbled as they wrestled to connect and the ball struck the Serb and wrong-footed Petr Cech in the process. Skrtel, alone in front of a gaping goal, could not believe his luck. Yet that is where their good fortune ran out. Sakho looped a header on to the bar from Henderson's delivery before that late penalty appeal signalled the end. This was not to be their day. It is Chelsea who go tearing into the new year.
Man of the match Eden Hazard (Chelsea)