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 tonight hoping for a victory that will take them one step closer to the knockout stages.
Even though Atletico have endured their worst start to a season since 1994, they have enough quality to upset their European hopes.
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 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.
“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.
“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. 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 can train a lot of things, but if someone falls asleep in a situation, we concede a goal.
“It's happened once now and, hopefully, it won't happen to us again.”
Chelsea v Athletico Madrid: Key battles
JOHN TERRY v SERGIO AGUERO
Argentinian striker Sergio Aguero is set to provide John Terry with a difficult evening. The Atletico ace has bags of experience even though he is only 21. A quality striker with an eye for goal, the Chelsea captain will have to be at his best. Terry and partner Ricardo Carvalho have yet to concede so far in the Champions League but they have not come up against anyone with the class of Aguero.
BRANISLAV IVANOVIC v SIMAO
The Chelsea full-back will almost certainly deputise for Jose Bosingwa even though the Portugal international is available again after suspension. And Ivanovic will have to be at his best to cope with the clever trickery of Simao on the left flank and he cannot afford to switch off against a player with his guile.
NICOLAS ANELKA v SERGIO ASENJO
It will may well come down to a shooting match between Chelsea's in-form striker Nicolas Anelka and Atletico goalkeeper Sergio Asenjo. Asenjo will find himself in the firing line with Anelka hoping to continue his form in front of goal. Asenjo has the agility to keep Anelka at bay but his confidence will be rocked if the Frenchman scores early.