After the final whistle Ruben Amorim trudged on to the pitch clutching his gilet, realised the next 10 minutes of his life would be better spent without a gilet and trudged off again to get rid of it. It was the only misstep of an extraordinary final evening at a raucous José Alvalade, during which his side conceded after just four minutes, somehow clung on to a single-goal deficit during an opening 35 minutes in which Manchester City threatened to bring his era to a jarringly humiliating conclusion, and then across a remarkable second half executed a joyful filleting of the English champions.

After this result the first thing Amorim will have to manage in Manchester is expectation, and that work started straight after the game. Asked if he had a message for United’s fans, he did not hesitate: “This means nothing,” he said. “Don’t take anything from this. We were lucky. It was a one-off. It doesn’t mean anything.”

Related: Rúben Amorim’s Sporting hammer Manchester City with Gyökeres treble

Clearly Amorim is not a natural limelight-basker, and if perhaps he did not fully embrace this occasion that was just about the only thing that went unhugged across an emotional final night in front of his home fans before he departs next week for Manchester United. Once he returned unburdened to the pitch after the game every player on his own side, and a couple on the other one, got a lengthy embrace.

Perhaps this was just a way of avoiding standing alone, and as staff and players went to the noisiest area of the ground to applaud the fans after the game he remained cautiously in the throng, and twice needed to be forcibly shoved – much as Josko Gvardiol did to Francisco Trincão at the same end during that wild start to the second half – clear of the group to soak up a little solo adulation. His night ended with him being rather messily tossed in the air three times – one thing his side had obviously not prepared for on the training ground – before ducking back down the tunnel and out of sight.

A couple of hours earlier he had been the last man out of that tunnel before the game, whereupon he shared his first hug of the evening with Pep Guardiola and strolled to the Sporting bench. But the idea that that would be all the attention he was going to get lasted only as long as it took for an epic – giant seems much too small a word for it – portrait, decorated with the single word “obrigado” – thank you – to be lowered in front of the opposite stand, and club president Frederico Varandas to beckon him on to the pitch to receive a framed poster. A large picture of Rúben Amorim emblazoned with the words Ruben and Amorim seemed a strange gift for actual Rúben Amorim, but some people are just hard to buy presents for.

What he must have wanted most of all was about to come, as a night that might have been tinged by sadness and regret became one of pure sporting joy and bewildered, bewildering noise. This is not a club that does things by half: they don’t so much have a pre-match anthem as an entire musical, a half-hour greatest hits set. Familiar songs, accompanying a wearily familiar dance.

In the summer Sporting lost 20-year-olds Abdul Fatawu to Leicester – after only a single senior start – and Mateus Fernandes – after just two – to Southampton. Over the last couple of years Pedro Porro moved to Spurs, Youssef Chermiti to Everton, Matheus Nunes to City via Wolves and João Palhinha to Fulham. Sporting’s director of football, Hugo Viana, will take up a similar position at City at the end of the season. And now Amorim. If the Premier League is good at anything, it is identifying a choice carcass, arriving in numbers, circling and scouting, and sporadically descending to tear away its sweetest flesh.

Related: Manchester United cannot play the way Sporting do, warns Rúben Amorim

And here they were, Sporting’s supporters, dealing with the man they credit with ending a 19-year run without a league trophy being ripped from their embrace, and expected to turn up and cheer as it happens. None of this is new for this club, and if the first cut is indeed the deepest they should be on to pretty superficial scratches at this point, but still it must sting. While the club’s allocation of tickets for Amorim’s final game, at Braga on Sunday, sold out in a single minute there were areas of empty seats behind both goals here.

At least Viktor Gyökeres, widely expected to be the next to get picked off, seemed to do his level best to put off potential suitors. Remarkably, despite spending much of the game strolling around in a variety of offside positions, seeming only occasionally interested when his own side had the ball and not at all when City did, and missing the two best open-play goalscoring opportunities of the game, he still ended it with a hat-trick and a tally of 23 goals in 17 games this season, so the suitors will be circling anyway. He is just going to have to try harder – that is, even less hard – in future. On this night, nothing Sporting did went anything less than perfectly.

“It was a beautiful evening,” Amorim said after the game. “I’m going to keep these memories forever.” That framed poster, though, perhaps not.