Pep Guardiola says "many, many things" went wrong as Manchester City suffered their first home loss of the season to Patrick Vieira's impressive Crystal Palace side.
Wednesday's surprise Carabao Cup exit at West Ham was compounded by a shock defeat for the reigning Premier League champions at the Etihad Stadium.
Wilfried Zaha got Pep Guardiola's 200th league match at the City helm off to a bad start and it got worse just before the break when Aymeric Laporte was sent off for bringing the Palace star down.
Gabriel Jesus saw an equaliser ruled out by VAR for offside and impressive loanee Conor Gallagher wrapped up a memorable 2-0 win late on.
"Could be yellow card or could be the red card," Guardiola said of Laporte's red card, having been judged to have denied a goalscoring opportunity. "It depends on the decision of the boss, the referee.
"The goal disallowed I didn't see but I imagine the linesman said it's offside.
"The goal we concede in Brighton it was offside and they continued, they score a goal, we didn't lose for that.
"We're not able to win the game, we conceded our first goal (at home in the Premier League this season) and after we work really well in the first half and, I would say, 25 to 30 minutes in the second one.
"But after playing for 45 minutes 10 against 11, a team like us we need the process and do everything right, that the people, the players, show character.
"But unfortunately it went wrong in many, many things and we lose the game.
"We conceded the goal early on but how many chances did they have? They had that goal and no more (in the first half).
"It is quite similar the last seasons when Crystal Palace came here under (Roy) Hodgson. We lost one game one year and we drew another one.
"It's the same process. It takes time to change the rhythm because the keeper all the time takes the momentum, long balls. They are good at keeping the ball.
"They have quality, they defend really well with solidarity and defend the gaps and block the shots. We cannot say that we had many but we had enough chances in the first half to score.
"When 10 against 11 it is more difficult, we scored a goal, it was disallowed and even Rodri had one or two chances to score. At the end, the counter-attack anything can happen."
It was a second Premier League win for Palace under Vieira, who began his coaching career at City having ended his playing days there.
Saturday's performance was comfortably the Eagles' best under the Frenchman, with impressive duo Zaha and Gallagher capping a superb team performance with goals.
"I think both of them, like the rest of the players, worked really hard," Palace manager Vieira said.
"We knew that coming to City we're not going to have the possession, so we have to work really well as a team and we couldn't allow ourselves not to have one player not taking part of the defensive work.
"I am really pleased of course for Wilfried for the goal he scored but I'm really pleased even more about how he worked with the rest of the team to make it difficult for City.
"I think we worked really well, we worked hard and when you come to a place like City and you don't concede a goal and you take your chances that's really good.
"But today I am really pleased because I see a side of the team that I didn't see before and I am really happy that we showed we are capable of defending well and defending well together."