After calling for more protection for players (all players, he was careful to add, not just his own), it was almost inevitable that Pep Guardiola’s Manchester City would have their quadruple dream ended by a red card dished out for an overzealous tackle.

It was a meaty one-footed smash that Fabian Delph unleashed on his counterpart, a tackle with max fury unleashed upon Max Power. Was it a red card? There’ll be a debate. It was one-footed, even if the studs were showing; he took the ball, albeit with plenty of the man; and it wasn’t as if Delph was trying to stop a counter-attack, flying in dangerously with no chance of winning the ball. Yet it was excessive and put his opponent in a position where injury was possible - then again, don’t most slide tackles?

To the traditionalists, it was a fever dream played out in real life: the Premier League leaders dumped out of the FA Cup as the oldest competition sprinkled its magic dust over a football match again, crushing the sophisticated foreign manager in the process. And yet, to the traditionalists, a meaty one-footed challenge would not usually merit a red card - but these days traditionalists are hardly minded to give Manchester City of all clubs the benefit of the doubt.

Soccer Football - FA Cup Fifth Round - Wigan Athletic vs Manchester City - DW Stadium, Wigan, Britain - February 19, 2018   Manchester City's Fabian Delph fouls Wigan Athletic’s Max Power and was subsequently shown a red card   Action Images via Reuters/Carl Recine

The irony is that Guardiola was hoisted by his own petard, upended by the same booby-trapped item he’d left for the others, like a mischievous child playing Mario Kart who later forgets about his own prank. There’s no small dollop of irony attached to losing a game thanks to a red card doled out in the name of player protection, but there’s also a sense of burning injustice that marching weren’t given to Cardiff City’s Joe Bennett, Crystal Palace’s Jason Puncheon or Tottenham Hotspur’s Dele Alli. It was Delph who received the punishment.

Then there’s an inescapable reality to deal with, too. This was a defeat which precludes City from winning an unprecedented quadruple. And although the FA Cup is rarely high on the top six clubs’ list of priorities at the start of the season, it is a bitter disappointment to lose out at this stage, with so much of the competition still to play.

But perhaps it’s also truly bitter because of what it points to. Guardiola’s City were so dominant before Christmas. Back then they were undoubtedly the best team in Europe, playing some of the absolute best football and blowing all competition away. Now, they’re still one of the best, but they’re not undisputedly the most in-form. The question now is if they’re peaked too soon.

https://video.footballfancast.com/video-2015/earliest-plwins.mp4

The answer is almost certainly yes - City were so good in the autumn that there is almost no way they could be better in the spring. In that sense, they have peaked too soon. On the other hand, that doesn’t mean they can’t grind their way to trophies now when it really counts. There will be pressure on Sunday’s League Cup final now.

The price of setting the bar so high is that missing it looks like failure where others simply fall much shorter. That's why it's strange to see so much schadenfreude doing the rounds. Two trophies is the ultimate success for Manchester United, Chelsea, Arsenal, Liverpool and Tottenham this season. No one can do any better than that. For City, two trophies is the bare minimum now. After having the title wrapped up by Christmas, anything fewer than a pair of shiny cups paraded around Manchester in June will be seen as scant reward for the football they’ve played.

The upshot is that City must win on Sunday to make sure of that second trophy to go with the Premier League title, and after that throw everything into the Champions League.

This is a bitter disappointment, make no mistake. But the disappointment isn’t just that the perfect season is gone, it’s that the level of dominance achieved in the autumn is no longer possible. And that means City are no longer invincible.

Even if the league is gone, every other team now knows that City are beatable which is great news for the rest of the top six. Four of them can dream of Champions League glory, but the belief starts for Arsenal on Sunday.