Tottenham put the brakes on Chelsea's title challenge
If the afternoon had started badly for Chelsea with Frank Lampard's second match-winning goal of the season for their title rivals Manchester City, it was safe to say it was about to get a lot worse. Jose Mourinho had never before lost a game to Tottenham and this was some way to have his record broken.
When the fifth Spurs goal went in, the defiance of the Chelsea manager slipped. Until then he had been berating the fourth official Andre Marriner and rearranging his team, but even he had accepted by then that this had been a rotten few days in the English Christmas football programme that he claims to love so dearly: two points dropped at Southampton and now a rare defeat at a despised local rival.
Their spell of dominance has been broken for now and Chelsea lead the Premier League on little more than the rule of alphabetical order: their record is identical to that of Manchester City down to goals scored and conceded.
Mourinho has refused to change his team and this time they looked jaded, not least the big hitters like Diego Costa and Cesc Fabregas who found themselves outplayed by a vibrant, attacking Spurs team.
After such an indifferent start to the season, Mauricio Pochettino must take great credit for his club's first win over Chelsea since April 2010 and his first over Mourinho as a manager. Their attacking spirit was embodied by Harry Kane whose two goals take him to 17 for the season and mark the further emergence of an unorthodox but beguiling English talent.
It was the kind of game you might expect at the end of a draining Christmas run of matches, and it was compelling entertainment. A Mourinho Chelsea team have never conceded four goals before, and when Nacer Chadli scored a fifth with 13 minutes left, the game was over. Yet Chelsea kept going and when John Terry scored his side's third there was an element of farce.
These kind of games, open and end-to-end, with defences run ragged and goals flying in, are not the brand of football Mourinho likes. All teams lose games, but this was the sort of chaotic defeat that will sting the most.
When Chelsea beat Spurs at Stamford Bridge in early December the door was shut and bolted, the game as good as over as soon as the home team took the lead on 19 minutes. This time the first goal for Mourinho's side arrived at roughly the same time, but Spurs' response was very different.
The away team were calling the shots for the first 17 minutes and when Costa scored the goal that gave Chelsea the lead, the story was taking a familiar shape. It was Hazard who made the chance, hitting a shot that struck the post. Oscar aimed for goal with the rebound and it fell for Costa who needed do no more than guide it over the line from close range.
But with Spurs vulnerable, Mourinho's side did not create the chances to score the second and they paid for it. Kane's marvellous equaliser came from nothing and it gave his team-mates the confidence to assert themselves.
There was nothing much on for Kane when he cut in from the left but one underestimates Kane at one's peril and as soon as he sensed the space to pivot and shoot he did so, pinging a right-foot shot beyond Thibaut Courtois' right hand and into the corner of the Chelsea goal.
For the final 15 minutes of the half, Spurs matched their opponents but most crucially they took their chances. A mistake by Cesar Azpilicueta turned over possession on 44 minutes and Christian Eriksen was in, slipping a ball through to Chadli whose shot struck the post. With the ball loose, Danny Rose got to it before Gary Cahill to score.
It was Cahill who gave away the penalty minutes later, once again he was fractionally late, this time on Kane and he clearly tripped the striker. It had become giddy at White Hart Lane even before Andros Townsend slotted his left-footed penalty past Courtois with the final kick of the half.
These are the kind of days that they live for at Spurs, although when they went three goals ahead six minutes after the break there was a mild disbelief. It was Kane again, spinning away from Matic and confidently placing the ball past Courtois.
Chelsea brought the score back to 4-2, Hazard exchanging passes with Fabregas to score.
Before the end, Mourinho reached across for the handshakes with the opposite bench, although it was with rather less flourish this time.