The champions were without key players and, in the absence of John Stones and Ruben Diaz, built a makeshift defence, which Bournemouth mounted with a fearless attack, backed by goals from Antoine Semenho and Evanilson, to beat City in the league for the first time.
Yosko Guardiola, one of a number of players to feature despite being a doubt before the game, scored with a late header to set up a frantic finish but it could not sustain City’s run as they slipped behind Liverpool on top of the table.
Of particular concern will be the ease with which Bournemouth’s attack, led by the excellent Semenyo and Justin Kluivert, tormented Nathan Ake and Manuel Akanji, neither of whom were fully fit.
“Ruben will be out until the international break,” Guardiola said. “Manu and Nathan put in an unbelievable effort to be out there in a demanding game, Kyle (Walker) too, 18 or 19 days without one training session.
“Rico (Luis) had a lot of minutes and he was also tired, so that’s the position we have, we try to manage the minutes. But we couldn’t do it. They were at a different pace today and we couldn’t handle it.”
The champions were also without Kevin De Bruyne and Jeremy Doku, only fit enough for the bench and were overrun at times. Milos Kerquez scored the first goal, getting around Phil Foden down the left and cutting in centrally for Semenho to turn Guardiola and head the corner to Ederson.
Ake in particular found the speed and direct flow of Bournemouth’s attack almost impossible to contain and City broke through again midway through the second half, Kerkez racing cleanly and crossing to where Ake and Guardiol had left Evanilson, giving the Brazilian place to choose finish.
“Sometimes we have to accept that the opponents play a type of game,” Guardiola said. “Sometimes you make it and sometimes you struggle a little bit. It happened today.
“(The players) are putting in an incredible effort. They are players who are not at their best and have made an incredible effort to be here.
“Manu and Nathan were not in good condition. I didn’t know Nathan could play until the last minute, he said I wanted to try.
“Sometimes during the season things like this happen more than during other seasons. We have to deal with it. People will come back and sooner or later the team will come back.”
Bournemouth boss Andoni Iraola, whose side climbed to eighth place after taking seven points from their last three games against City, Aston Villa and Arsenal, reflected on the fearless performance of his players.
“We had to feel the pressure and it was tight in the end,” he said. “I am very pleased. It’s one thing to beat City, but another to play better.
“We played without fear, tried to press when we could and defend when we had to.
“It was dangerous in the last 10 minutes. You don’t like that at all. There was so much pressure.”