Leicester City travelled to Manchester to face an injury-ravaged City side, who had only 13 players fit for selection. The Foxes had a good track record against the Cityzens anyway, so this was certainly a chance for them to steal some points off Pep Guardiola's men and perhaps even get back to the top of the Premier League table.
An exciting clash was set to ensue, and here's what we made of it.
City started off well and won a corner in the 4th minute. Kevin De Bruyne's delivery was headed away by James Justin, but it only fell to Riyad Mahrez around the edge of the box. The ex-Leicester man had a hit on the half-volley with his 'weaker' right foot and picked out the top corner with some help from the inside of the far post.
The hosts had a chance to double their lead in the 17th minute after Riyad Mahrez slipped Raheem Sterling in on the right following some very good work by Kevin De Bruyne. The Englishman couldn't get a proper connection on his shot, and it was easily saved by Kasper Schmeichel.
The hosts could have made it two in the 25th minute as well, when Kevin De Bruyne's free-kick was headed from close range by Fernandinho. The Brazilian's effort was straight at Schmeichel, however, and it was caught with ease.
Despite City's dominance, they conceded a penalty in the 36th minute after Jamie Vardy got goal-side of Kyle Walker and was subsequently brought down. The striker stepped up to take it, and emphatically converted.
Then, in the 53rd minute, a quick passing move from Leicester saw Timothy Castagne run down the right. He delivered a great low cross for Jamie Vardy, who cheekily flicked it past Ederson.
Four minutes later, Eric García tangled with Jamie Vardy in the box, and Leicester had another penalty. The talismanic striker stepped up yet again, and this time he found the bottom corner with a great finish.
City nearly pulled one back in the 64th minute as teenager Liam Delap met a quick cross with a header, but only managed to clip the crossbar.
Leicester added insult to City's injury in the 77th minute. Substitute James Maddison got on the ball on the left hand side, drove inside and then unleashed a curler straight into the top corner
The hosts pulled one back in the 84th minute as Nathan Aké headed a corner in to score his first goal in the colours of Manchester City.
But then, in the 87th minute, Benjamin Mendy decided it was his turn to give away a penalty as he pulled James Maddison down in the box. Youri Tielemans stepped up, and dispatched it.
Too Early for a Crisis?
Pep Guardiola was already downplaying his side's chances pre-match considering the fact that they only had 13 fit senior players.
His side started off brilliantly, and took the lead in the 4th minute thanks to a brilliant strike from Riyad Mahrez. They had quite a few chances to double their lead, but they failed to take them and then they were made to pay. Defensive errors certainly played a part as they conceded three penalties, and City will undoubtedly be blaming themselves for this defeat.
Yet, losing in such a manner and with such a scoreline has to be worrying in spite of the lack of senior players. Conceding five goals in one match is never good for any top side, even if you are lacking central defenders. It's too early in the season for the alarm bells to be ringing, but this has to be treated as a wake-up call by the Cityzens.
Oh, and they need to sign Rúben Dias rather quickly now.
And that's how the match ended - 2-5 to Leicester
Ederson (4), Kyle Walker (4), Eric García (5), Nathan Aké (5.5), Benjamin Mendy (3.5), Fernandinho (5.5), Rodri (6), Phil Foden (4.5), Kevin De Bruyne (6), Raheem Sterling (5), Riyad Mahrez (7*)
Subs: Liam Delap (5), Ferran Torres (5)
Leicester narrowly missed out on a Champions League spot on the final matchday of the previous season, so they were certainly looking to set things right this time around.
The stats were against them, as Brendan Rodgers had never beaten Pep Guardiola in the past. Their start wasn't great either, but they dug in and stuck to their plan. After holding on for a while, they sprung forward on the counter and caused all sorts of problems for City.
The manager must take credit for his smart game-plan which he looked to have formulated following the schooling he got at this very ground in the last campaign. But, the players and Jamie Vardy (more on him soon) in particular should also be praised for a brilliant display. Things seemed to click perfectly for the Foxes, and they'll want to keep playing like this for the rest of the season.
However, let's not hype them up too much as we did in the last season, because we're only three matches in.
Kasper Schmeichel (5.5), Timothy Castagne (7), Daniel Amartey (6), Çağlar Söyüncü (6), Jonny Evans (6.5), James Justin (7.5), Nampalys Mendy (7), Youri Tielemans (7.5), Dennis Praet (6), Harvey Barnes (6.5), Jamie Vardy (9*)
Subs: James Maddison (7), Christian Fuchs (N/A), Kelechi Iheanacho (N/A)
Before this match had kicked off, only two men had scored a hat-trick against a Pep Guardiola's side - Lionel Messi and Jamie Vardy.
The English striker went clear on this occasion, as he haunted the Cityzens once again with a brilliant display. He started off by winning and dispatching a penalty, before giving his side the lead with an outlandish flick. Soon thereafter, he made it three by earning and converting yet another spot-kick.
The 33-year-old finished the match with 3/3 shots on target and 2 penalties won from just 21 touches of the ball.
Clinical stuff once again from the current Golden Boot holder.
What This Means
City slump to 13th spot in the Premier League, while Leicester go back to occupy first position. Leicester became the first side in the competition's history to win three penalties in a single match, and it also means City have lost their first home match of a new campaign for the first time since 1989.
City travel to face Burnley next in midweek in the EFL Cup's fourth round, while Leicester meet West Ham next weekend.
Stats courtesy whoscored.com and Opta