Michael Ballack has revealed how Chelsea's players held a training ground inquest into the set-piece errors which are threatening to disrupt their season.
Chelsea face Atletico Madrid in the Champions League at Stamford Bridge on Wednesday night hoping for a victory that will take them one step closer to qualifying for the knockout stages.
But even though Atletico have endured their worst start to a season since 1994, they still have enough quality to upset Chelsea's European campaign.
Chelsea are becoming increasingly concerned with the defensive errors that allowed Aston Villa to inflict a second successive away defeat on the Blues last Saturday.
Chelsea lost 2-1 with both goals being conceded from corners. Captain John Terry was furious with their defensive lapses and Germany midfielder Ballack, who missed the game with an ankle injury, revealed the squad are determined to eradicate the mistakes.
"John's reaction on the pitch showed that he takes a big responsibility not just for himself but for the team,'' said Ballack. "He was really disappointed when we conceded the second goal.
"That's what you need, emotions like that, to make sure it doesn't happen again. We speak with each other. We have no problem criticising each other in the dressing room. A good team with strong players has to do this. We've done that, then we shake hands and get back on to the training pitch and try to do better.
"I wasn't involved, not in the team, but I know the problem. I was there the next day and we spoke about it. Everybody has to make an impact on the situation, me too.
"I have to do this, not just because of my age. I have a few years behind me and have experienced a few situations. I'm experienced, so I have to speak to help the team. Everybody has to take responsibility, otherwise we will concede more goals.
"It's a little bit unusual to concede twice, which is why we were so disappointed after the game. We played well, which makes it all the more disappointing. We've watched the game on TV at Cobham. We saw who made the mistakes, and everyone knows that, but in football people make mistakes.
"We've spoken about the game, we've trained on set-pieces and special situations, but it's all about individual mistakes. That happens in football, but that's what we have to cut out. We have to work on it because it's happened again on Saturday. It was just one game, but it was obvious we lost that game on set-pieces."
Coach Carlo Ancelotti admits his team have spent time working on set-pieces ahead of the clash and a win for Chelsea would put eight points between them and the Spanish side.
"We have worked on this particular situation but it's not important just to work on this,'' said Ancelotti. "We have to pay attention on set plays in the game. It's difficult to train for set-plays, just like it is train for penalties. You're changing the situation, which is always different.
"But we have worked on them because we have to improve. You can play good matches, like we did at Aston Villa, but if you don't pay attention for six seconds - for one set-play - you come away with a bad result.
"This is not good. We have to put in a good match tomorrow, too, and we have to win it. The match tomorrow is important because we have a possibility to move eight points from Atletico Madrid, and this would be very good. We want to maintain our position at the top of the group because we want to win this group. Tomorrow we have a good opportunity to do this.''