Defender Kolo Toure admits Manchester City have to find an answer to their defensive problems if they want to remain in the hunt for trophies.
A much-changed team slipped to a surprise 4-2 defeat at home to Aston Villa in the third round of the Capital One Cup having twice taken the lead.
Roberto Mancini's side have conceded 14 goals in seven matches - 16 in eight matches if the Community Shield is counted - and have yet to keep a clean sheet.
Conceding two late goals in the Bernabeu cost them a famous victory against Real Madrid last week and now one of the four competitions they would have expected to challenge in has slipped through their grasp.
Defensive errors certainly cost them against Villa and Toure accepts it is a concern.
"It was a disappointing night," he said.
"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 every body so when you lose it is everybody."
After the defeat Mancini accepted his side had been poor and that defensively they needed to tighten up.
"This is a problem. We need to work with our defenders because they don't work well at this moment," said the Italian.
"When the situation is like this we have to understand our mistake and do our best for the future."
Toure's foreseeable future seems destined to be on the bench as, after just one start and a substitute appearance prior to last night, he was hoping a good cup run would give him more pitch time.
But now that avenue has been closed off to him and several others the focus has to be on ensuring he is still able to do a job for the first team should he be called upon.
"It is disappointing to go out," he told CityTV.
"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.
"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."
City are still awaiting an update on midfielder Jack Rodwell's groin injury after he pulled out of the starting line-up having been injured in the warm-up.