If this really was to have been Pep Guardiola’s 24th and final Wembley appearance as the Manchester City manager, then he went out in trademark fashion – as a winner, as an overseer of magic moments. There was actually only one of the latter here, but it will stand the test of time, Antoine Semenyo lighting up an FA Cup final that had previously been heavy on perspiration rather than inspiration.

The Wembley clock showed 72 minutes and, at that point, it was a Chelsea team desperate to put their recent woes behind them who were in the ascendancy. Was Calum McFarlane, their red-raw rookie caretaker coach, about to produce the sling-shot to fell Guardiola? Were the unhappy Chelsea supporters about to get something to save their season?

Enter Semenyo. When the ball was worked by Bernardo Silva up the right to Erling Haaland, Semenyo dropped off in the middle for the low pass from his teammate, but he was closely marked by Levi Colwill. When the ball came, it was also a little bit behind him. No matter. Semenyo let his instincts take over and the result was a scintillating flick with his trailing leg that diverted the ball perfectly into the far corner. The vision was matched by the technique and there was no way back for Chelsea.

The buildup had been dominated by talk of Guardiola’s future, with the hard-to-ignore feeling being that he will walk away from City at the end of the season. With the Premier League title looking out of reach, Arsenal so close to it now, he had been even more determined to add another FA Cup to the Carabao Cup secured in March. Thanks to Semenyo, he did so, this his 17th major trophy in 10 years with City (not including the three Community Shields).

City had lost in the previous two FA Cup finals, but it was Chelsea who felt the heartbreak on this occasion; yet more heartbreak. It was their seventh domestic cup final defeat in succession. The reset under their next manager – who the club hope will be Xabi Alonso – cannot come quickly enough.

What a challenge it was for McFarlane in his sixth senior game as a manager and the former City youth coach went for solidity – three centre-halves; Reece James and Moisés Caicedo providing further ballast in central midfield.

Guardiola’s move at the outset had been to pick Omar Marmoush in place of Rayan Cherki and start him high alongside Haaland. It was 4-2-4 with Semenyo and Jérémy Doku on the wings. The Marmoush call did not work and he was replaced at half-time by Cherki.

City dominated the ball in the first 45 minutes, Chelsea happy to invite them on, but it was a slow-burn period to put it kindly. The atmosphere was subdued, Wembley speckled with empty seats.

It was not until the 20th minute that Chelsea made an inroad into the City half, Matheus Nunes heading behind from a Malo Gusto cross and what happened next was indicative. Chelsea played the corner short and ended up working it all the way back to their goalkeeper, Robert Sánchez.

City had a few flickers in the first-half, but their finishing was unconvincing. There was a weak volley from Marmoush early on, a wild slash from Haaland and an even wilder one from Semenyo when his shot went out for a throw-in. Haaland had the ball in the net only Nunes was offside before he crossed. City’s best moment came on 43 minutes when Marc Guéhi threaded a good ball up the inside-left channel for Haaland, who drew a block out of Sánchez.

Enzo Fernández looked to go in on Bernardo Silva with excessive force in the 29th minute – it was yellow rather than red – while Chelsea’s appeals for a penalty before half-time were waved away. Abdukodir Khusanov banged into João Pedro, but it was shoulder to shoulder. The City defender looked to play the man.

There were errors on the ball from both teams. James Trafford was guilty of one at the start of the second half, taking a heavy touch on a back pass and allowing the ball to roll out for a corner. From it, the goalkeeper’s punch was weak and Rodri needed to be alert to clear Caicedo’s looping header from in front of the line.

Semenyo had gone close with a header on 47 minutes – a good chance wasted – but it was Chelsea who summoned the greater intensity after the restart. They flexed their muscle in midfield where it was not a day for Rodri. He did not look fit on his return from injury and was withdrawn for Mateo Kovacic.

The game narrowed to a fine point, the likelihood increasing that it would take only one moment. Perhaps it would be a borderline decision from the referee, Darren England. Or maybe a moment of brilliance. That appeared less likely, but then Semenyo intervened.

England came under heavy pressure to award Chelsea a penalty with another round of loud cries coming in the 77th minute when Khusanov barged into Jorrel Hato. The City defender played on the edge. England was unmoved. Fernández had volleyed high on 74 minutes and it was City who might have added a second goal in the closing stages. Nunes rattled the near post from a tight angle while Cherki extended Sánchez. One was enough for City.