Pep Guardiola played down concerns over Aymeric Laporte's absence after Norwich took full advantage of defensive frailties to beat Manchester City 3-2 at Carrow Road.
Without the injured Laporte, who is out until the new year after knee surgery, the City back-line were not up to scratch as the Canaries ran out shock winners, live on Saturday Night Football.
Goals from Kenny McLean and Todd Cantwell had the newly-promoted side deservedly ahead before Sergio Aguero pulled a goal back on the stroke of half-time.
- Report: Norwich 3-2 Man City
- How to watch Premier League highlights on Sky
- Latest Premier League table
- Why Laporte injury could cost City the title
But, with Kevin De Bruyne surprisingly only named as a substitute, the much-anticipated comeback never materialised as Teemu Pukki added a third after awful defending from Nicolas Otamendi.
A late strike from Rodri was little consolation for the visitors, who suffered their first defeat of the season to give Liverpool a five-point lead at the summit.
John Stones and Otamendi only started three times in the Premier League last season, but Guardiola dismissed suggestions his side now have a glaring weakness.
The Catalan told Sky Sports: "It's a partnership that has played a lot. We've got Fernandinho and Rodri who can play there in other situations and it's not a worry. Things happen.
"We didn't expect the injury and in more than three years together John and Nicolas have played together, and thanks to them we've won.
"Laporte is injured and Kompany is now in Anderlecht, and so we cannot just analyse it off one game. We need to improve on that and hopefully we can do better."
Having hauled back the deficit, Otamendi and Stones survived one mix-up as Pukki raced onto a ball, only to skew his shot wide - but seconds later the striker made amends.
Stones rolled the ball to Otamendi on the edge of the box and as the Argentinian dallied, Emiliano Buendia nipped in to steal possession and lay on Pukki's sixth goal of the campaign.
Guardiola slumped to his knees after the setback, but bullishly added: "I know what we are as a team, I know what we've done and I know what we will do again.
"I love my players, it's a pleasure and an honour to be with them, but it's a challenge at the highest level. We cannot expect to win every time and to reach over 90 points.
"We are going to have to recover, we head to Europe now, and then we will come back.
"We knew the quality of Norwich and we've had a lot of days to work on it. Conceding goals is part of football, and in the end we pushed a lot, but I must congratulate Norwich."
'Laporte injury could cost City'
Jamie Redknapp told Sky Sports: "The Laporte absence is the story right now, make no mistake about it. I felt that in the summer, they had to recruit after losing Vincent Kompany.
"Matthijs De Ligt went to Juventus and he had the profile of everything City like to buy, Harry Maguire went to Man Utd and it was unusual for them because their recruitment is usually spot on.
"You can't foresee an injury like Laporte's when he's out for six months, but you have to be ready for every eventuality. Right now, it is looking like it could cost them."