The reigning champion had been without a victory in four games and that run looked like stretching in the most unlikely circumstances when Elijah Adebayo headed in for Rob Edwards’ side on the stroke of the interval.

City was missing the injured Erling Haaland – with in-form winger Jeremy Doku also ruled out – and looked set to remain seven points off the Premier League summit as Luton bravely held its lead beyond the hour mark.

Then, Pep Guardiola’s side burst to life to revive its title defence, with two goals in three minutes from Bernardo Silva and Jack Grealish turning the game on its head as a famous upset was narrowly bypassed.

City came at Luton from the off. Inside two minutes, Phil Foden broke into the box down the left and stung the palms of Thomas Kaminski, who beat his effort away well. From the rebound, Silva lashed wide with a hurried miscue when greater composure was required.

Rodri was next to test Luton’s goalkeeper, drawing a fine one-handed save after unleashing a fierce drive from 20 yards, before the Belgian made his third and finest save of the opening half-hour, diving low to keep out Foden’s bullet effort with a firm wrist.

City though was getting closer. Julian Alvarez dinked one wide at the near post, getting on the end of Grealish’s intelligent ball into the six-yard box but finding only the side netting.

But the longer Luton held out, the more frustrated City appeared to become.

The final 10 minutes of the first half saw Guardiola’s side reduced to speculative efforts from outside the box, either closed down by the hosts’ tireless defence who never let City rest on the ball, or sailing harmlessly behind Kaminski’s goal.

Then came the moment that stunned the champions. It began in midfield with Ross Barkley, showing sublime strength and skill to hold the ball, spin and release Alfie Doughty racing down the right.

He moved it on to Andros Townsend, who checked from his right foot to his left, lifted his head and – with a raking cross – found Adebayo rising at the far post between Kyle Walker and Ruben Dias to head Luton into the lead from a yard out.

The hosts had come within seconds of beating Liverpool and drawing with Arsenal here this season and looked determined finally to earn a win against one of the league’s top sides and to put pressure on 17th-placed Everton in a bid to escape the relegation zone.

On the hour mark, Dias rattled the crossbar from Nathan Ake’s cut-back in what was the visitors’ first real opening since falling behind.

Within minutes they were level and it was the architect of Luton’s goal Barkley who was at fault, losing the ball in midfield to Rodri who drove at the heart of the defence.

He collided with Tom Lockyer who had come across to challenge and as the ball broke loose, it was pounced upon by Silva, barley glancing up at the goal before thumping it impudently first time inside the far post.

Seconds later it was 2-1 and it was the simplest finish for Grealish. Alvarez’s low cross evaded the desperate lunge of Teden Mengi, arriving at Grealish’s feet six yards out.

With Luton’s defence breached, he had time to take a touch, decide on his spot and stick the ball calmly between Kaminski’s legs to the relief of visiting supporters behind the goal.

Luton’s spirit was unbroken and it sought an instant riposte. Barkley ran round Foden and Mateo Kovacic and sent a fizzing right-footed drive inches past the post.

From that point, City was never comfortable and Luton did not look beaten until the very end, but City hung on to end its barren run.