Pep Guardiola admitted Manchester City "could not handle" the intensity of Bournemouth after falling to a 2-1 defeat on the south coast.
Goals from Antoine Semenyo and Evanilson saw City fall to a 2-0 deficit for the first time since January 2023 (against Tottenham), before Josko Gvardiol headed in what proved to be a consolation late on.
The defending champions had been struggling with injuries in the build-up to the fixture, leading to a bench with an average age of 23 years old.
Guardiola blamed those injury troubles for his side's failure to get back in the game at the Vitality Stadium.
"We knew we couldn't match the intensity. We have talked about it. It was an open game. We had chances at the end but I congratulate Bournemouth for the victory," he told BBC Sport.
"The 50-50 balls in the middle, the duels, they play this type of game. They are so aggressive. They had six, seven days to prepare. They have physicality and speed, but you have to win these types of situations.
"We have few players with a lot of minutes and a lot of players with no minutes to the balance is a bit uncomfortable. We played good against Spurs but today we could not handle their intensity that they had and that's why we lost the game."
City still managed to accumulate a higher expected goals (xG) total, finishing on 1.8 compared to Bournemouth's 1.74.
That was boosted significantly when struggling Erling Haaland saw a header saved in stoppage time before crashing the rebound against the base of the post from close range.
"We had real good moments at the start of the second half and after that it was difficult to swallow as we were good. After we scored we had momentum and chances but couldn't score [again]," added Guardiola.
It was an entirely different story for the hosts, who registered a third home victory on the bounce, after defeating City's title rivals Arsenal in October.
"It was a great game. We did everything we could. We needed our very best performance and not the greatest game [from City] and that happened. It is very good to beat City and even better to beat them deservedly," enthused Andoni Iraola.
"It is very difficult. They are a great team. They have amazing subs and you have to suffer, stay compact. We suffered after a good game. We had the chance to finish it and not suffer too much at the end, but now we have to enjoy it.
“We know there are better teams than us but it is not easy to play here and we have to keep this level so everyone knows that when they come here it will not be an easy game."
The victory came in no small part due to the standout performances of Semenyo and Milos Kerkez
Semenyo was central to every Bournemouth attack and accumulated 0.56 xG and created three chances, the highest in his team.
Kerkez proved instrumental, too, delivering both assists off the left wing, first beating Kyle Walker to drive to the byline and cut back for Semenyo's opener, before providing a brilliant cross for Evanilson to prod in Bournemouth's second.
"They played very well the last few games and today they had the finishing product. Milos had two assists, we felt he deserved to get the numbers and I am happy as it was a complete performance," added Iraola.
"To beat a team like City you need everyone to play really well and they did."