The Blues were torn apart by Pep Guardiola’s men and were 4-0 down in 25 minutes
Cesar Azpilicueta has branded Chelsea’s 6-0 hammering to Manchester City “unacceptable” and one of the worst days of his career.
Sergio Aguero’s hat-trick, Raheem Sterling’s double and Ilkay Gundogan’s strike condemned the Blues to their heaviest defeat since Nottingham Forest beat them 7-0 in 1991.
Defender Azpilicueta told the club’s website: “It’s difficult to find the words to describe my feeling after the game.
“It is one of the worst nights in my career. It’s very frustrating, it’s very disappointing.
“When you lose 6-0 everyone has to accept they didn’t play well. The only thing I can say to the fans is sorry, because it’s not acceptable, and I feel sorry for all of them.”
Chelsea have lost three of their last four Premier League games, with their only win coming against bottom club Huddersfield.
The Blues face City again in the Carabao Cup final on February 24.
Azpilicueta, who conceded the penalty for Aguero’s third goal, said: “We have lost big games in the first minutes and we are conceding a lot of goals. We cannot accept that.
“We knew we had one of the best teams in front of us and we knew it would be tough.
“When we won against them at Stamford Bridge it was because we played a very good game all together. This time it was not the case. To lose in this way is very disappointing.”