Despite taking an early lead through Riyad Mahrez, the visitors managed to get in behind the City defence on a number of occasions and when they did, they invariably punished some hesitant defending.
The Foxes were awarded three penalties, Jamie Vardy bagged a hat-trick in the 5-2 loss.
It was our first opening home game defeat in the top flight since 1989.
City wasted no time in pinning Leicester back in and around their own box and were ahead with less than four minutes on the clock.
Kevin De Bruyne’s corner was cleared to the right of the box where Mahrez was lurking and the Algerian will probably never hit a ball cleaner or sweeter as he hit a right-foot shot that arrowed like a missile into the top left corner of the net.
It was the perfect start on a beautiful autumnal afternoon at the Etihad.
Few could have predicted what lay in store, however.
City continued to boss possession, but the Foxes continued to sit deep and had a couple of dangerous counter-attacks that suggested this would be anything but a straightforward 90 minutes.
City had a few half-chances to double the lead and on 34 minutes, only the assistant referee’s flag prevented Rodri’s header from making it 2-0 – and in their next attack moments later, the Foxes won a penalty.
Vardy raced on to a pass in the box and Kyle Walker’s clumsy (though unintentional) challenge floored the Leicester striker resulting in a spot-kick that Vardy thumped home.
It was the visitors’ first shot on target, but the warnings had been posted.
Nine minutes after the re-start, Vardy put the Foxes ahead, as Castagne broke free on the right, crossed low into the six-yard box and the Leicester No.9’s clever flick gave Ederson no chance.
Vardy then completed his hat-trick a couple of minutes later with almost a carbon copy of the first goal as he ghosted in behind Eric Garcia who collided with the Leicester striker and gave a second penalty away.
Vardy tucked it home confidently to put City in a rare position of being 3-1 down at the Etihad - but it would get even worse.
Suddenly, the long list of injuries and lack of pre-season looked to be taking it’s toll, but with more than half-an-hour remaining, the danger was the visitors could inflict more damage.
And they did.
Sub Liam Delap came close to reducing the deficit on 65 minutes when he headed a cross onto the post, but that had to go in for the hosts to have found a way back into a game that, for the first third, had been fairly comfortable.
It got even bleaker for the City when James Maddison curled a long range shot over Ederson on 77 minutes to make it 4-1 in what was already a thoroughly miserable afternoon for City.
Incredibly, referee Michael Oliver awarded a third penalty on 87 minutes as Benjamin Mendy caught James Maddison and Tielemans converted to make it 5-2 and complete a nightmarish 90 minutes.
What it means…
With two games played, City are in thirteenth.
City travel to Burnley in the Carabao Cup on Wednesday evening (kick-off 7pm), looking to progress to the quarter-finals.
Then it’s off to Elland Road to face a resurgent Leeds United next Saturday (5.30pm kick-off).