It really was what they said it might be – a Group of Death – and it has all but certainly deposited Manchester City from the Champions League at the first hurdle once again. But what we saw here last night was an act of self-immolation, a defeat which confirms that the club's own failings are the problem on an evening of dreadful defending and few chances created.
Plunged to the bottom of Group D, even wins in all three pool games left will provide no guarantee of progress and City may be playing for a Europa League place when Ajax come to Manchester, two weeks from now.
Mancini started with a back four that had never before played together in Europe, with Joleon Lescott's start perhaps reflecting the manager's realisation that the more offensively minded Matija Nastasic is not yet the big-game player he envisaged. There was a solid, old-fashioned Englishness about James Milner and Gareth Barry holding midfield.
But from the start it looked as if Frank de Boer's youthful charges might overwhelm City. Christian Eriksen, the brightest talent in the local firmament, was the best player on the field early on, turning Barry so elegantly and easily to open up space and fire wide on 20 minutes.
Two minutes later Samir Nasri found the goal which, for a time, settled nerves. Milner was instrumental, seizing the opportunity of only his sixth start in a season when his City star has seemed to be dropping. He controlled Micah Richards' speculative ball from the right and guided it carefully into the path of the Frenchman, whose sweetly struck first-time shot was his third goal of the season.
But even as his side led, Mancini was switching things significantly, restoring Yaya Touré from the advanced midfield three where he started in a 4-2-3-1 to the core of a 4-4-2.
Even so Ajax equalised on the stroke of half-time when the right back Ricardo van Rhijn took on a firm 30-yard cross-field pass from Siem de Jong, delivered a quick but rather trundling cross back into the area, and watched no fewer than three City players fail to deal with it. De Jong stepped up past an immobile Nasri to take the ball back and thump it past Hart and put the Dutch side level.
It got much worse. When Eriksen wafted a corner over from the right just before the hour, Lescott was simply outjumped and overpowered by the advancing Niklas Moisander, whose header put the Dutch side up.
Finally, the coup de grâce. Lasse Schone stole the ball from Barry and fed Eriksen. Kompany's studs seemed to get stuck in the turf as he advanced to challenge, as the Dane eased around him and fired off a shot Gael Clichy deflected dismally into his own net. Game, and Europe, over.