It was a penalty to potentially seal the Premier League title... but has Sergio Aguero's missed Panenka helped give Chelsea a Champions League boost?
This was supposed to be a fitting finale, Aguero scoring the goal that seals Manchester City their fifth Premier League crown, just like he did for their first.
But the Argentine's first-half miss, chipping the ball into the air and watching Chelsea goalkeeper Edouard Mendy catch it one handed, allowed Chelsea a route back into the game.
It remains a case of when, not if, Pep Guardiola's side win the league, with their lead still 13 points after a 2-1 defeat by Chelsea at Etihad Stadium.
Nearest rivals Manchester United have two games in hand, but City only need three points from their remaining three games to clinch their third title in four years.
Guardiola will likely be more concerned that his side head into the Champions League final with back-to-back defeats by Chelsea, who also beat them in their FA Cup semi-final.
'He never scored them in training'
Manchester City led 1-0 when Billy Gilmour fouled Gabriel Jesus in the box and Aguero stepped up with the chance to strengthen his side's grip on the trophy.
Instead, his tepid effort was lofted slowly into the gloves of Mendy and Chelsea went on to turn the match around in the second half.
"If the penalty goes in then we get the game over and done with," Raheem Sterling, who scored City's opener, told BBC Match of the Day.
Boss Guardiola was asked whether it was a "selfish" decision by Aguero.
"Listen, he is selfish because he missed it. If he scored a goal you would say how [much of] a genius he is," he said.
"That's the reality. I say to the players in the penalties take one decision: Panenka, right, left, short, whatever you want, but commit. He was committed, if he misses it, he misses it.
"Everyone is disappointed but the first disappointment is him, you know that. He's a sensible guy. We're not going to talk about what Sergio has done, how he's been for this club, for this team for all this period he has been here, so he took the decision and that's all."
Micah Richards, Aguero's former team-mate, said the penalty was "harsh" but could not believe when the 32-year-old missed it.
"I had my head in my hands, I couldn't believe he did this, it is just a bad penalty," he said on Sky Sports.
"You think, 'Sergio Aguero, get on the scoresheet, slot it home, we want you to do it in style...' but Mendy reads it.
"He used to do this in training but never used to score, so I don't know why he has tried it."
Aguero, who will leave the club at the end of the season, has scored 10 goals against Chelsea in the Premier League, more than any other player against the Blues.
But he has now missed two of his past three penalties in the English top flight, and City have failed to score from the spot on a league-high four occasions this season.
The home side did think they should have had another in the second half when Kurt Zouma tangled with Sterling in the box, but the decision was not given,
"We miss the first. The second was not given. That's all," Guardiola told BBC Sport. "It's a penalty. It's a penalty, I don't know about VAR, the officials know why they didn't give it."
'Chelsea have been handed a psychological boost'
Three weeks ago, Manchester City still had an unprecedented quadruple in their sights.
Thomas Tuchel's Chelsea beat them in the FA Cup semi-final to end that dream and the sides will meet again in the Champions League final in three weeks' time.
Chelsea head into that game with successive victories over Guardiola and City, and the Blues boss says it gives them "confidence".
"This result won't change the final," he added. "It is a unique game, you can't predict what will happen, there will be changes, but we arrived with the knowledge we are capable of beating them."
Despite both sides making a host of changes from the line-ups that secured their place in the Champions League final in midweek, Richards believes the victory has handed Chelsea a "psychological boost".
"Pep has kept his cards closest to his chest by not playing his strongest side," he said "But confidence wise it would have been nice to get over the line. If you are going to lose today's the day but you cant make those mistakes in the final."
Where does it rank among worst Panenkas?
Aguero is not the first - and certainly won't be the last - to fail to reproduce Antonin Panenka's winning chipped spot-kick for Czechoslovakia at Euro 76.
Gary Lineker couldn't help himself after watching Aguero's effort, the former England striker produced a terrible Panenka attempt of his own against Brazil at Wembley in a warm-up for Euro 92. Had he scored, Lineker would have equalled Sir Bobby Charlton's then record tally of 49 goals.
And it has been a good season for awful Panenka penalties.
Ademola Lookman's attempt with the last kick of the game in Fulham's 1-0 defeat at West Ham is certainly up there with the best of them, with his weak effort dropping tamely into Lukasz Fabianski's hands.
A missed Panenka is bad, but a missed Panenka in an important match is something else.
In 2010, Leicester's Yann Kermorgant attempted to chip the ball over Cardiff City goalkeeper David Marshall in a Championship play-off semi-final penalty shootout, but his spot-kick was comfortably saved as the Bluebirds marched on to the final.
Meanwhile, Peter Crouch scored a hat-trick in a 6-0 win over Jamaica to round off England's World Cup preparations in 2006.
But it looked like he had missed his chance at netting a treble when he sent an attempted Panenka into the stands.
Here he is discussing that moment on BBC Radio 5 Live's That Peter Crouch Podcast: