Manchester City fell to a third defeat in just four home league games, as Thomas Tuchel's Chelsea side delayed Pep Guardiola and his player's Premier League title celebrations by at least one more day.
Despite Raheem Sterling's opener just before half-time, an abysmal Sergio Agüero penalty opened the door for a Chelsea comeback, which was completed in the dying seconds by full-back Marcos Alonso.
Here's what we learned from a disappointing day at the Etihad Stadium...
Sergio Agüero's Worst Miss?
I take no pleasure on ripping into Manchester City's best ever forward- so I won't, because his horrendous "Panenka" penalty doesn't ultimately matter. We'll still win the Premier League, maybe even on Sunday, and nobody will remember his miss this time next year.
But it was still shocking, and probably cost Manchester City the win on Saturday afternoon. It was only one part of a generally bad day for the Argentine, though.
Moments earlier, he had been vocal in his frustration with Raheem Sterling, who had committed the heinous crime of scoring a goal after Sergio Agüero nearly ruined a great chance.
It felt very out-of-character for a striker who usually plays with a smile on his face, and may have contributed to his decision to go for the spectacular when the spot-kick came his way.
A Case of Inevitable Disjointedness
When you make nine changes and play a back-five with only one true midfielder, you're basically asking for a disjointed performance. It's pretty remarkable when you start to list the names who didn't start today - Kevin de Bruyne, Ilkay Gundogan, Riyad Mahrez, Phil Foden, John Stones, Fernandinho and more...
When you put it like that, it's clear to see why Manchester City struggled to score goals. It's no excuse - the quality of the starting XI was still very high despite all our rotation - but it was arguably the formation and set-up that hindered us more than the team selection.
The formation was borne out of necessity, as Pep Guardiola tried to fit almost everyone who didn't start on Tuesday night into the same squad. The comfort is that it's not representative of how good Manchester City will actually be in the Champions League final, meaning we could spring a surprise on Chelsea - or is that clutching at straws?
Fernandinho's Grip on a UCL Final Spot Tightens
If Fernandinho's sensational performance against PSG in midweek wasn't enough, the disastrous moment where Rodri gave the ball away for Chelsea's equaliser has surely all but guaranteed that the Brazilian will be in the starting XI in the biggest game in Manchester City's history.
Rodri has had a very good season all in all, but it's so frustrating to see that he's still making big mistakes in big games like that one. The only thing between him and a top player is cutting out those errors, or at least making them less frequent, and they're odd to see from such a level-headed and clearly intelligent player.
Fernandinho, despite being 36 now, just feels too good to leave out at this moment in time...
Sterling a Bright Spark
There were signs in the Carabao Cup final that Raheem Sterling was starting to play his way back into form, and that was certainly evident today. Not only did he open the scoring with a finish reminiscent of his instinctive shooting in earlier seasons, but he caused the Chelsea defence more problems than any other City player by running at and behind them.
He was also unlucky not to get a penalty, which was one of the key talking points from the match. Late on, Sterling went down after a challenge in the box - but not even the VAR deemed it worthy of awarding a spot-kick.
It's a real shame, because I have a feeling Raheem would have taken that one himself and could have added yet another big moment to his repertoire.
City's Last Game As Title-Chasers?
With Manchester United forced to play three games in five days, including a visit to Aston Villa and home fixtures against Leicester City and Liverpool, it seems very likely that Manchester City will be Premier League champions by their next game (a trip to Newcastle next Friday night).
The title race hasn't been close for a long time now, but it will be over next time United drop points, or if Manchester City beat the Magpies- whichever happens sooner.
It will be interesting to see what Pep's team selection policy is like for the remaining league fixtures. He could use it as an opportunity to hand more minutes to players like Eric García, Zack Steffen and Tommy Doyle, but there are also benefits to keeping our best players sharp and raring to go ahead of the Champions League final.
We'll get a better indication on Friday night...
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