Joe Hart made an error-free return to action but Manchester City left it late to secure victory over Viktoria Plzen in the Champions League.
Goals from Alvaro Negredo and Edin Dzeko in the last 12 minutes finished off the spirited Czech minnows as City won 4-2 at the Etihad Stadium in their latest Group D fixture.
Plzen had twice come from behind to level with goals from Tomas Horava and Stanislav Tecl after Sergio Aguero, from the penalty spot, and Samir Nasri put City ahead.
Goalkeeper Hart, playing his first City game for a month, was not at fault for either of the goals conceded and impressed with some good saves - but the same could not be said for the rest of the defence.
Despite goals flowing at the other end - 22 in the last four home games - questions have recurred about the back line throughout the season, particularly with captain Vincent Kompany out injured.
Manager Manuel Pellegrini said: "One of the most important things to be an attacking team is to know how to defend well. Today we did very, very bad.
"I am talking about the whole team. I think the whole team must know how to defend."
Pellegrini was at least pleased with Hart's performance but would not say whether he would remain in goal for Sunday's Barclays Premier League visit of Swansea.
The England number one lost his place earlier this month after a series of errors and had sat out City's previous five games, with Costel Pantilimon playing in his place.
Pellegrini said: "I think Joe Hart played very well.
"I didn't expect that he would have to work so much during the game but I think this is the match when the other team - including Champions League and Premier League (games) - had the most chances to score.
"Today I am not thinking about Premier League. From tomorrow, we will start thinking about who is the best XI to start for the next game, from the goalkeeper to the other players."
City's win meant they retained hope of finishing top of Group D, although they will need to beat champions Bayern Munich convincingly in their last game to do so.
They made hard work of the victory as, after a bright opening in which Nasri hit the bar, they allowed winless Plzen to ease back into the game.
Aguero looked to have banished worries by converting from the spot for his 15th goal in 12 games after a handball by Frantisek Rajtoral, but Horava cancelled it out with a powerful strike.
Nasri volleyed City back ahead but again Plzen responded, with a well-worked Tecl goal.
Pellegrini said: "I am satisfied because we won the game 4-2 but I don't think we played well.
"We didn't play with the intensity and the pace we have been playing with here at home."