This was a result, a performance and an occasion to cherish for Cardiff supporters. This was also a shock to enliven a Premier League season that has been slow out of the blocks.
This was historic. They have not seen football from the leading division on home soil since West Ham United were defeated at Ninian Park on April 23, 1962. The Cardiff faithful never gave up hope, even during the darkest days, the trips to the High Court and the selling of talents from John Toshack to Aaron Ramsey.
They always believed.
Even against such celebrated guests. Manuel Pellegrini's side have so much money, so much talent. They have spent almost £100 million ($199 million) this northern summer. They tore Newcastle United apart and even took the lead through Edin Dzeko here. But the fans believed.
That emotion was heard in every chant, in every derisive whistle at the vaunted visitors, in every cackle as Manchester City's defensive issues were exposed first by Aron Gunnarsson and twice by Fraizer Campbell, a former Manchester United striker eager to add to his one England cap.
Understandably angered by the board's ill-judged, tradition-shredding decision to change their strip from blue to red, a group of Cardiff supporters had marched from the Castle to the ground, demonstrating against the affront, yet the club still felt united here, all pulling in the same direction, all seeking to survive and prosper in the Premier League.
This was a display and a triumph for all those members of the club's staff, the backroom souls and club servants who kept the flame alive, who kept the place running even, who've given everything to the club they love. It was a nice touch by Mackay to acknowledge such unsung heroes afterwards.
That collective hunger was seen in the way Mackay's players set about Manchester City with particularly outstanding contributions coming from Gunnarsson, who was tireless in midfield at disrupting and creating, from the line-leading, two-goal Campbell and from the tall sentries Steven Caulker and Ben Turner.
In truth, all of Mackay's players deserve praise, and none left the field with shirts unstained by sweat.
This was no fluke. This was deserved. Mackay outwitted Pellegrini. He set the right tone throughout, a figure of commitment and calm in the dugout. Mackay's jacket was soon off, almost as if transmitting a message of getting down to work.
Afterwards, he waved modestly but this was a huge win for him in his nascent managerial career. It will make future team-talks easier. His players know their bright young manager can devise game-plans to thwart even title favourites.
