The veteran Leicester forward scored a hat-trick – two of them penalties – to inspire a sensational comeback.
And more than two years after retiring from international duty, this came in front of watching England boss Gareth Southgate.
Vardy couldn’t go back at 33 – could he?
This five-star Foxes display looked impossible as Manchester City took an early lead and appeared to be cruising.
But the home side had no answer to the veteran’s pace as his two spot-kicks – both of which he won himself – sandwiched a cheeky near post finish.
And there was still time for James Maddison to curl in a beauty and Youri Tielemans – again from the spot – to complete a quite incredible afternoon.
City’s new centre-back Ruben Dias is due to join up on Monday in a deal worth around £64 million.
If he saw the way his new team-mates defended in a calamitous 21 minute spell either side of the break he might decide to stay in Lisbon.
A Pep Guardiola team conceded five for the first time in his managerial career.
He had spoken about beforehand about having only 13 fit senior players – and no strikers but it didn’t seem to matter early on.
Mahrez – who was a key man in Leicester’s fairytale title four years ago – had spoken about his wish to score against his old pal Kasper Schemichel.
The ‘Algerian Prince’ did it here last year – albeit via a deflection – and clearly fancied his chances again.
He had to wait four minutes – and this one was an absolute beauty. Kevin de Bruyne’s corner was nodded away by a back-pedalling James Justin.
It sat up nicely for Mahrez but Schemichel barely saw it as his first time rising effort flew into the top corner. And with his right foot as well.
The £60 million man was sidelined earlier this month after testing positive for Coronavirus – he is clearly not suffering any after effects.
City threatened to run away with the game as Rodri blazed a shot over and Sterling fired one straight at Schemichel.
De Bruyne floated over a free-kick that was perfect for Fernandinho but he planted his header straight at the Danish keeper.
Another free-kick from de Bruyne was almost identical to the last one and this time Rodri headed home but the Foxes were rescued by a linesman’s flag.
And they made the most of the reprieve as they were level minutes later.
A pass from Harvey Barnes found Vardy in the box and he was held back by Walker who got the wrong side of him.
Vardy himself stepped up to slam home the spot-kick and score his third penalty already this season.
It was their first shot on target – and Pep Guardiola looked seriously fed up about it on the sidelines. This is exactly the kind of thing that happened all too often last season.
City began the second half on the front foot again with De Bruyne firing a shot wide early on.
But just five minutes had gone when Guardiola ordered young striker Liam Delap to get ready from the bench against Leicester City.
The 17-year-old had scored on his debut on Wednesday night against Bournemouth on Wednesday and his manager obviously felt his physical presence was needed.
Yet no sooner had he come on, his team were suddenly chasing the game.
Leicester’s Youri Tielemans sent Thomas Castagne away down the right and his low cross was cheekily turned in at the near post by Vardy.
Leicester City saw one good shout for a penalty waved away before they did get one as Garcia clumsily challenged Vardy and Michael Oliver pointed to the spot.
This time he went low to Ederson’s left and completed his hat-trick.
In doing so he became the first player to score a treble against City since…yep, a certain Jamie Vardy did it almost four years ago.
City’s creaky defence simply had no answer to the pace of Vardy and Leicester’s counter attacks.
That was the cue for Guardiola to replace Phil Foden – with the England youngster struggling to make an impact in front of Southgate.
Leicester were happy to sit back, not surprisingly, and allow the hosts to try to break them down.
A header from Delap bounced on top of the bar while De Bruyne’s cross just eluded the out-stretched foot of Sterling.
Yet they were always vulnerable on the break and sure enough within 10 minutes of coming off the bench Maddison curled a stunning fourth over Ederson.
Summer signing Nathan Ake nodded City a lifeline five minutes from time but the comeback never looked on.
And sure enough Mendy clipped Maddison in the box to give them a third penalty of the day – you couldn’t argue with any of them.
Leicester’s Vardy had gone off a couple of minutes earlier – so Tielemans stepped up…but the outcome was the same as Ederson once again didn’t get close to it.