At half-time we were looking at a Premier League massacre, with the Manchester City fans bouncing and journalists scrolling through the Blues’ biggest victories, just in case.
By the end, it was a comfortable win, courtesy of goals from Kevin De Bruyne, Riyad Mahrez, Ilkay Gundogan, Raheem Sterling twice and Aymeric Laporte but not before a stunning Leicester fightback had turned the Boxing Day jubilation into silent nervousness.
And once it was over, it was one for the compilation tapes of wild, unpredictable festive fixtures, a wonderful treat, even for those strange individuals who find City “boring”.
It was also a vindication of Pep Guardiola’s pre-match words, that his midfield and full-backs cannot defend, other than by keeping the ball off the opposition for long spells.
That was drummed home in spectacular fashion as the Blues front six, ably backed up by Joao Cancelo and Aleks Zinchenko, tore a gaping hole in the Foxes, racking up a 4-0 halftime lead, but then looked vulnerable and defensively inept as they dropped a gear and gave the visitors a sniff of a memorable comeback.
That was snuffed out as City added further goals from Aymeric Laporte and Raheem Sterling, but it all added up to a marvellous festive treat of a match.
Guardiola had coyly talked about his team’s “weaknesses” just before Christmas, making the point that his midfielders and full-backs are “not good defenders” and that the Blues cannot hit teams with pacy attacking in the way Liverpool do.
The defending was irrelevant, as City simply kept the ball for long spells, but Stering was maybe stung by the notion that the Blues cannot match Jurgen Klopp’s side for the pace of their attacking.
He was especially revved up from the start, flying past Kieran Dewsbury-Hall and repeatedly exposing the Foxes right flank.
Revenge is rarely cited as a motive in football, but everyone knows it exists, and players smarting from an embarrassment tend to sharpen their claws to an even greater extent.
Last season, with no fans at the Etihad, Leicester racked up a shock 5-2 win that cast early doubts over City’s title credentials – doubts that were eradicated as they stormed back.
Only five of the team that played that day were on the pitch as this one kicked off, but City looked like a team intent on repaying the Foxes for the blushes they caused that day.
That result was certainly avenged, but not in the overwhelming way it looked like it would, at half-time.
Out of the blocks like an Olympic sprinter, regardless of the fact that the influential Rodri was missing – Raheem Sterling was in turbo-charged mode down the left and with Bernardo Silva and Riyad Mahrez weaving intricate patterns down the right, the Foxes felt like the Boxing Day hunt had returned.
It was no shock that the Blues were ahead by the fifth minute, and just as at Newcastle, it was quite a gift, in some ways.
Another forceful, bewildering City raid seemed to have petered out, but Fernandinho delicately lifted a pass over the defensive line and De Bruyne was onto it.
With three defenders near him, he looked to have little on, but they stood off and allowed him to bring it down, shift it onto his left foot, and crash it home.
Leicester were bold in their response, but that just left them more vulnerable, and they were in trouble again as they defended a corner.
Ruben Dias was tangling with former Blue Kelechi Iheanacho, but Youri Tielemans went too far when he wrapped an arm around Aymeric Laporte.
The Spain international went tumbling in the box and the VAR invited ref Chris Kavanagh to take a look on the pitchside monitor. He deemed the contact was solid enough to warrant a spot-kick, and Riyad Mahrez smashed it high into the net.
Still the Foxes showed ambition, and when James Maddison curved a free kick towards the top corner, Ederson leapt across to turn it onto the crossbar and be mobbed by teammates who recognised the importance of the moment.
Buoyed by it, City stormed forward again, playing bewildering, bewitching football that was a little too heady and sharp for the hungover heads in the stand, never mind the shell-shocked Foxes.
It was soon 3-0 as Bernardo jinked and juggled his way in from the flank and exchanged passes with De Bruyne until Joao Cancelo raced wide to open up space.
He fired a cross that was close enough to keeper Kasper Schmeichel to tease him off his line, but he could only palm it straight to Gundogan, and he gleefully placed it in the unguarded net.
There was no mercy, no Christmas benevolence shown by the Blues, and it was 4-0 by the 25th minute.
Sterling, who was in a ravenous mood, dashed into the box and darted past Tielemans, still harbouring a grudge from conceding the first penalty.
This time there was no dispute, as he stuck out a lazy leg to trip Sterling. Mahrez moved towards the ball but Sterling was even too quick for him, racing in to grab it and place on the spot.
Schmeichel tried a little gamesmanship, arguing about something with the ref while Sterling listened, a picture of calm disinterest, and then thumped his spot-kick into the top corner.
It was an absolute feast for the eyes, and Sterling was denied another when Aleks Zinchenko lifted a pass for Bernardo who, with prescience and glorious touch, volleyed it into Sterling’s path. He hit it first time on the volley and Schmeichel acrobatically hurled himself skywards to turn it over the bar,
That first half had people currying for the record books – the Blues were in that kind of mood.
But they changed down a gear after the break, and their subdued approach encouraged a stung Leicester team.
They hit back when Laporte slipped on halfway to send Kelechi Iheanacho away – he delayed his pass until the perfect moment and Maddison had a simple finish.
“We scored a goal” sand the visiting support, followed by “We’re gonna win 5-4”.
That was tongue in cheek, but when they bagged another one with 14 minutes of the second half played, there was suddenly some jeopardy for the Blues.
Iheanacho again did the damage, striding forward and feeding Ademola Lookman, who slipped his shot past Ederson for 4-2.
For all their sureness and dominance in the first half, City suddenly looked vulnerable, and the “we can’t defend words” of Guardiola became pertinent – and the Foxes sensed a famous comeback.
It was on after 65 minutes when Maddison curled a shot onto the bar and Iheanacho tucked away the rebound.
The mood around the ground had gone from buoyant confidence and celebration at half time to tense unease, and it took a setpiece goal to settle nerves again.
Mahrez swung a corner from the right and Laporte atoned for his earlier error by unerringly heading it into the top corner, perfect placement to make it 5-3.
Leicester still hammered away for a fourth goal, but City gradually re-asserted their dominance.and ended any argument when Ruben Dias headed Mahrez’s corner goalwards and Sterling darted in to tap in his second of the match.
So City march on at the top, and Jack Grealish continued to kick his heels on the bench, the punishment for his indiscretion in going for an ill-advised night out last week.
Phil Foden saw a degree of forgiveness for his part in that escapade, playing the last 20 minutes as a sub, but with with Sterling, Mahrez and the rest in this mood, the two errant players might wonder when exile from the starting line-up will end.