Antonio, Antonio. And still, just about, Antonio. Never mind the tide of snark on social media, or the sense of death that attaches itself to the endgame of every Chelsea manager; the travelling fans still sing Antonio Conte’s name with the same protective affection as they did from the start at the King Power Stadium.

Chelsea kept their season alive here, edging past Leicester City into the FA Cup semi-finals. But this was also a victory studded with a sense of what might have been in another, happier second Conte season.

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Most obviously there was a scoring return to the Chelsea attack for Álvaro Morata, in a week when Conte had adopted the fashionable posture of wronged superstar manager, the coach whose only failings are the failings of others, betrayed by the workaday qualities of the human clay at his disposal.

Conte has suggested his players overachieved in winning the title last year, credit naturally to his own transformative powers. But even Prospero has a limit to his magic and the suggestion is that Conte clearly was under-backed by his generals.

It is a position that sits uncomfortably with the addition this year of a £60m centre-forward who has been left to limp along as an ill-fitting part through the difficult days since Christmas. Morata came to the King Power Stadium having played 42 minutes of football this month and having failed to score since Boxing Day.

Conte can moan about his players being beneath his attentions but this is still a high-grade £60m centre‑forward, a player Conte has now been involved in signing twice, in a team that has played to his weaknesses and dwelt on his flaws.

Not so much here, though. Instead for an hour Morata provided a gathering sense of life at the point of the Chelsea attack, on the kind of night where the wind scrapes the face like a blunt razor blade and when even the idea of spring, of sun and warmth, seems almost inconceivable.

Play Video 0:42 Antonio Conte pleased with Chelsea's character after FA Cup win at Leicester – video

The reservations about Morata’s style have centred on his preference for scooting on to through-passes, finding clever angles, rather than holding the ball with his back to goal.

It is a tribute to Diego Costa’s all-round bile-ridden craft that he offered both options in the same grizzled package. Could Conte have worked at this with Chelsea’s record signing, dredged a little more from him or even adapted his attacking plans? Apparently not. Easier simply to whinge and bridle, to linger on the flaws in his squad, the impossible black holes.

Before kick-off the former Real Madrid and Juventus man had been introduced to the crowd, a little vaguely as “Alvaro Marato”. But he ran eagerly from the start, even if there were some early clanks and groans.

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Midway through the first half Morata was left writhing on the floor after a lunge by Wes Morgan that applied the full weight of that sack of gravel masquerading as a right thigh to Morata’s big toe.

He did not stop, though. Like a rusty racing bicycle easing through the first few revolutions of its wheels, chain clicking, brake blocks hissing, Morata did start to find space, looking ever more menacing as Chelsea held the ball or found space for a cross.

The goal was coming. It arrived on 42 minutes, made by Willian, such a wonderful surging presence in the last month. Easing away from a knot of Leicester players in midfield, Willian looked up and threaded in his centre-forward with exactly the right kind of pass, a pass that might have been wrapped with a ribbon and decorated with “Álvaro” in blue frosted icing. Morata seized on it like a starving man, hared in on goal and finished with a beautifully easy shift of his body, slipping the ball nicely past Kasper Schmeichel’s left hand.

And suddenly he looked confident, shark-like, romping about with a sense of menace. In part this was a function of Chelsea having so much more possession in the first half, a 60-40 split that removed the need to fight and haggle and scrap for the ball, and freed Morata to make those little runs off the centre-backs.

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Leicester found some encouragement as Chelsea slackened. Riyad Mahrez had been particularly disappointing, even his fetching lop-sided canary yellow pie crust hairstyle seeming to droop as the second half wore on. But he began to find his passing range and Jamie Vardy sniped in to grab an equaliser.

Pedro headed the winner in extra time. And a minute later Morata left the pitch having run hard and shown at times a real gloss of class in his touch and movement. Indeed, to watch him here was to wonder again why his time at Chelsea has been so disappointing since a fine scoring performance against Atlético Madrid in September. Conte offered faint praise for his “strength” afterwards and this was an admirable return in many ways.