Kolo Toure has warned his Manchester City team-mates that they must improve defensively if they are to achieve success this season.
City were beaten 4-2 at home by Aston Villa on Tuesday night, crashing out of the League Cup in the process.
Roberto Mancini's side have now conceded 14 goals in just seven games, and are yet to keep a clean sheet this season.
"It was a disappointing night," Toure told CityTV after the loss.
"The team didn't play well. We conceded four goals, which is not good, and we gave some cheap goals to Villa as well.
"It concerns us because a team like Man City cannot expect to concede four goals at home.
"Since the season started we have not had a clean sheet and that is very important when you want to be a top club, you have to defend better as a team.
"As a defender and as a group we have to work on it because mistakes were done by a few players and when you win it is everybody so when you lose it is everybody."
The clash with Villa was used by Mancini to field those on the fringe of his squad, including Toure, and the Ivorian sees the outing as a missed opportunity to impress the Italian.
"For us we don't have a lot of games to play in and this was a chance to have a few games but we've wasted that," Toure added.
"I think it is going to be hard maybe to play now but we will work hard to try to get a chance to play in the Premier League."