Oh, Sergio. A reminder from Mr Guardiola to all boys – particularly those who are leaving the Etihad Campus at the end of the year. Term is not over. The final exam is not yet passed. And this really isn’t the moment to start having fun.

This was an odd, increasingly gripping game. A 2-1 Chelsea win only delayed the inevitable title celebrations for Manchester City. But it carried a genuine significance for Thomas Tuchel, firming up the likelihood of a top four finish and ensuring his future employment to – shall we say? – at least November.

Whatever happens from here, the last half-season has been a startlingly assured and lucid period of coaching-on-the-hoof from a man who really does look and sound like he’s enjoying himself to an indecent degree right now.

It took a while to get there. At times in the first half Manchester City and Chelsea seemed to be dishing up the kind of weekend fare we might have witnessed under the Super League regime – players rested, feints and bluffs in play, a game with another game on its mind.

At which point a football match broke out, pegged around an act of unexpected slapstick in first-half injury time from a man who has 182 Premier League goals to his name and has earned a degree of balls-of-steel arrogance.

With 44 minutes gone Raheem Sterling scored the opening goal, made by a fine surging run from Gabriel Jesus. His cross evaded the cover. Sergio Agüero produced an unintended assist, his clumsy touch taking the ball to Sterling, who finished easily.

At that moment City looked to be entering that place, the podium zone. All the more so as they were awarded a penalty in stoppage time after more fine, ferrety work from Jesus.

Agüero took the ball with a chance to kill this game, to kill the title race, and to ease the whirring in his manager’s mind over rest and downtime and game management.

At which point, Agüero decided to go for the panenka. “It was his decision,” Pep Guardiola shrugged, doing a decent, if unconvincing impression of a man who is, like, totally cool with this kind of thing – details, whatever – and hey, it’s just a game.

Pep Guardiola and Thomas Tuchel will do battle again in the Champions League final.
Pep Guardiola and Thomas Tuchel will do battle again in the Champions League final. Photograph: Getty Images

It was a poor panenka – caught with embarrassing ease by Édouard Mendy – and a poor decision from a man who looked vague all afternoon. On the touchline Guardiola could be seen striding towards the tunnel, limbs stiff with rage, hood bouncing primly.

His mood will have been further darkened by Marcos Alonso’s late winner, and by the fact City should have had a penalty shortly before as Kurt Zouma challenged Raheem Sterling clumsily from behind. At the tail-end of a season where penalties were at one stage being given for halitosis, unkind remarks and the mere possession of fingers and arms, it looked like a refereeing mistake.

But Guardiola will also have found some clarification of his own as both teams look towards that end point in Istanbul (or similar). Nathan Aké and Benjamin Mendy will not form City’s defensive right flank, where Timo Werner was once again a source of incision.

Sterling scored his second goal at the Etihad since 5 December. He still looks keen – a man constantly trying to fight his way back to that other place, the version of his own reality where the game becomes easy and the ball is once again his friend. He isn’t there. But his movement is a weapon against this back three. Then there was Agüero, who has been a rapier for so long but didn’t look anywhere near the level of that starting team for the season finale.

Mainly this was Tuchel’s day. In the FA Cup game Chelsea had found space behind City’s full-backs. Guardiola fielded a counter-move of his own here, the great midfield fetishist going cold turkey and picking a starting team with five defenders.

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City still played a high line, and at times Chelsea’s high press caused problems. Werner loitered high up the field, spending much of his time in a role that can only be described as “offside”. There was a point to this. In that space he is a constant scattergun danger. He gave the assist for the winner. He worked, as Tuchel said, “like a dog”. With better timing – or indeed any timing – in his runs he could have scored a couple himself.

Chelsea’s equaliser with an hour gone came down that familiar channel of interest, this time on the right, Hakim Ziyech burying his shot expertly past Ederson’s left hand. Guardiola has a problem to solve there.

And so on we go, a little closer to the endgame. City will be a different team in three weeks’ time. But this was a significant step for Tuchel on several fronts.