Jamie Vardy ended his goal drought with a fabulous hat-trick as a revitalised Leicester tore apart a dreadful Manchester City to leave Pep Guardiola facing searching questions.

Guardiola’s side played into the Foxes' hands and were cruelly exposed by a Leicester side who finally rediscovered the swagger of Premier League champions.

Vardy led the way, scoring a typical treble after 16 club appearances without a goal. But Leicester, for whom Andy King also scored a memorable goal, were aided and abetted by opponents who defended high up the field and left Vardy with the space he relishes racing into.

A shambolic defensive display from Guardiola’s men left questions still hanging over whether the Spaniard’s successful methods from Spain and Germany will transfer successfully into the Premier League.

They followed up a costly defeat to Chelsea last weekend with another chastening loss despite late goals for Aleksandar Kolarov and Nolito.

King doubled Leicester's lead with a long-range effort (Getty)

For Leicester, though, it was a hugely welcome return to form after a difficult defence of their Premier League title. The champions made a fabulous start as Vardy ended his long wait for a goal to cap an excellent move.

Riyad Mahrez produced a sublime touch to cushion a high ball into the path of Islam Slimani, whose sliderule pass for Vardy was almost as impressive.

The England forward drifted away from Aleksandar Kolarov and despatched a low shot past Claudio Bravo and into the bottom corner with a finish that showed none of his recent nerves.

Ranieri was still digesting that moment when, two minutes later, his team doubled their lead with another excellent goal.

Christian Fuchs’ long throw was headed on powerfully by Robert Huth and Slimani again provided the assist with a neat lay-off.

But the goal was all about King, whose curling strike from the edge of the penalty area flew in off the fingers of the despairing Bravo.

Things might have got even better for the hosts in the 12th minute when another header down from Huth found Slimani but the Algerian could not adjust his posture sufficiently to direct a shot on target.

The much-maligned Bravo had a day to forget (Getty)

Manchester City had barely stirred in the opening 15 minutes but they threatened Leicester’s goal when the home side failed to clear from the edge of their 18-yard box, allowing Kevin De Bruyne a shot that flashed a couple of yards wide.

That was a false dawn, however, and their gloom deepened on 20 minutes when Vardy added his second thanks in no small part to another moment of magic from Mahrez.

The PFA player of the year produced an outrageous touch to divert Christian Fuchs’ 50-yard pass perfectly into the feet of Vardy, who rounded Bravo and coolly slotted home.

It could have got even better two minutes later when a revitalised Mahrez weaved his way past a series of of defenders but saw his shot turned away by Bravo.

Manchester City screamed for a penalty in first-half stoppage time when Kelechi Iheanacho went down under a clumsy challenge from Marc Albrighton.

But their appeals were waved away and Leicester should have ended any doubt over the result seconds later when Albrighton’s cross found the unmarked Slimani, who headed wide with the goal at his mercy.

Early in the second half the visitors applied pressure on the hosts and they threatened to reduce the deficit in the opening moments.

Both Pablo Zabaleta and De Bruyne had shots blocked in a frantic goalmouth scramble with De Bruyne appealing half-heartedly and unsuccessfully for a penalty for handball against Fuchs.

Stones hangs his head after Vardy notches his third (Getty)

Ilkay Gundogan then sent a shot just wide after a lay-off by Iheanacho as Guardiola’s side continued to peg back Ranieri’s.

But Leicester had the opportunity to settle any tingling nerves among their supporters when Slimani drifted into space in the visitors’ penalty area, only for his shot to be kept out by Bravo.

Vardy made it 4-0 on 78 minutes when he completed his hat-trick in trademark tenacious style.

He pounced on a dreadful pass from England colleague John Stones and scored from a tight angle with the goal awarded thanks to goalline technology.

And even a fabulous curling free-kick from Kolarov four minutes later to make it 4-1 and a side-footed finish by Nolito in the final minute could not spare their side from embarrassment.

Boss Pep Guardiola would not criticise his team's defending after they had found themselves two goals down inside five minutes.

He said: "We defended well with these players at the beginning of the season and we played good teams at the beginning of the season so now we have to analyse the mentality of players to make a step forward. All managers need time.

"We tried until the end, always in one game there are some good things but it's difficult at this level when it's 2-0 after a few minutes."

Leicester City (4-4-2): Zieler; Simpson, Morgan, Huth, Fuchs; Mahrez (James 90+1), King, Amartey, Albrighton; Slimani (Okazaki 77), Vardy (Gray 88).

Subs not used: Chilwell, Musa, Hamer, Mendy.

Manchester City (4-1-4-1): Bravo; Zabaleta, Sagna, Stones, Kolarov; Fernando; Navas (Sterling 58), Gundogan (Nolito 68), Silva, De Bruyne; Iheanacho (Toure 58).

Subs not used: Caballero, Sane, Clichy, Abarabioyo.

Referee: Michael Oliver