Why Aguero's 30-minute cameo may have been the spark that changes Manchester City for ever
Sometimes, it just takes a spark.
A player who can turn a good side into a title-winning side.
A player who suddenly seems to solve all the niggling problems and the misfires.
A player who ignites all the good players around him and whose very presence makes everything fall into place.
So forgive the excitement and forgive the impression that maybe we're all getting a little bit carried away.
And don't think anyone's forgetting that, for £38million, Manchester City fans should be entitled to think a forward ought to be a bit special.
But to be at the Etihad Stadium and to witness the Man City debut of Sergio Aguero felt like being in on something momentous.
It felt like a landmark.
Yes, the Argentine striker was only on the pitch for half an hour.
Yes, it was only a cameo.
And yes, he was only playing against a tiring Swansea side whose best moments of the night were long gone.
But of all the superstar arrivals that have happened here in the blur of transfer activity that has taken place since Sheikh Mansour bought the club three years ago, it's Aguero's that feels as if it has the power to transform the side.
There was an electricity about the place when he came on for Nigel De Jong. There was a feeling that something special was about to occur.
Certain players carry that magic along with them.
Like Wayne Rooney did when he made his Manchester United debut in September 2004 and scored a hat-trick against Fenerbahce.
There has been a feeling until now that City are a worthy side, a solid side, a team full of quality players but with the exception of Carlos Tevez, who has been a restless presence, a team lacking stardust.
Under the cautious, counter-attacking tutelage of Roberto Mancini, they have often failed to capture the imagination.
Even while winning the FA Cup and qualifying for the Champions League, they have been damned by faint praise.
The arrival of Aguero, who cost £13m more than the entire Swansea starting XI, threatens to change all that.
Other players may arrive before the end of this window, but none of them will be as important as Diego Maradona's son-in-law.
Swansea played some beautiful football in the first half but as the visitors were demolished after the break, it felt as if the grand design of City's jigsaw is nearly complete.
There is room for more creativity in midfield, certainly.
They would probably be better and certainly more attractive without both Gareth Barry and De Jong in the starting line-up.
But the arrival of Samir Nasri would improve that and in all other areas, City are formidably strong.
David Silva is the best technical player in the Premier League and the surging power of Yaya Toure at the heart of the side is often breathtaking.
Their defence, led by Vincent Kompany, who was at his indomitable best against Swansea, is solid and, in attack, they now have an embarrassment of riches.
It still seems unlikely Tevez will be here after the end of August, but Aguero's arrival also means that Mancini no longer has to indulge the idiosyncrasies of Mario Balotelli, with whom he is fast losing patience.
So, yes, it was only half an hour.
And yes, it was only a tiring Swansea.
But Sergio Aguero changed something last night.
He made City and their fans believe that their time has come.