Just when the doubters were gaining traction and Manchester City were beginning to feel that missing out on Lionel Messi was no big deal, reality struck in the French capital and reminded us all that we’ve been kidding ourselves.
The biggest question being asked ahead of this Champions League group stage tie was a complicated and double-sided one.
Would the arrival of Messi help PSG finally achieve the burning ambition of their owners by bringing the big-eared trophy to Paris? And would failing to sign him, despite having the Argentinian’s long-term mentor as manager, come back to haunt City as they strive for an identical goal?
The sheer quality of Messi’s stunning goal in a 2-0 victory, even though it flattered the hosts, has answered the second question and shortened the odds on an affirmative answer to the first one, too.
These are two clubs with a lot in common.
Both owned by powerful and wealthy men from the Middle East, both relatively new to the world stage and both dreaming of European glory having won everything there is to win in their own countries.
With that in mind, City’s refusal to join the race for Messi when he was made available is difficult to comprehend. He would, surely, have taken them to another level and he would certainly have made a difference in this fixture, in which City played well enough and created chances but without finding the net.
The decision not to pursue a free transfer came in a summer when City’s rivals at Old Trafford were willing to fund a move for Messi’s old rival Cristiano Ronaldo — and in which they failed to land top target Harry Kane in the transfer window.
The fact that Pep Guardiola is in charge at the Etihad, a man who won 14 trophies together with Messi in his Barcelona days, and who has maintained a strong relationship ever since, makes the mystery all the more unfathomable.
Perhaps it was the fact that having ruled out a move for the Argentina star the previous season it was difficult for City to backtrack, especially after spending €120m on Jack Grealish instead.
Perhaps the signing of a 34-year-old, however talented, went against the long-term principles that have underpinned the club’s remarkable rise.
Or maybe the desire to bring in Kane still burns strong despite Tottenham’s reluctance to part with him and proved a more important consideration.
Whatever the truth, it’s hard not to see the decision as an opportunity missed in the short term, especially when the primary goal this season is to become European champions and deliver the trophy that owner Sheikh Mansour truly craves.
The fact that Messi had a hand in the opening goal and then scored a wonderful second should not come as a big surprise, of course, but there had nevertheless been concerns in Paris that their new man had not been the instant success he was expected to be.
Messi started the tie without a PSG goal to his name and with memories of a lacklustre 1-1 draw against Club Brugge in their opening match of Group A still hanging uncomfortably in the Paris air.
His part in the opening goal, driving forward to set up Mbappe to cross for Idrissa Gueye to score, wasn’t enough on its own to persuade the football world that all was well, especially as he spent much of the ensuing match sitting deep and failing to impact the game in the way you would expect.
But patience is important when players move clubs and the little magician’s mazy dribble, followed by a quick one-two-with the impressive Mbappe and then an arrowed left-foot finish, ended the debate and underlined his enduring class.
By contrast, City — who once again lined up without a recognised striker — struggled to finish the chances they created, especially when Bernardo Silva hit the bar from only a metre out; and that’s a recurring theme.
You suspect both these teams will go on to make the knockout stages, even though City have dropped to third in the table temporarily; but if you added Messi into Guardiola’s side they’d be far bigger favourites in every competition they play, that’s for sure.
That’s something the English champions cannot dwell on ahead of Sunday’s trip to Liverpool in the Premier League; but it’s a nagging feeling that may never leave them unless they go on to lift the Champions League trophy in St Petersburg in May.