Chelsea players were sharply critical of each other after their 2-1 defeat by Aston Villa and have been practicing defending set pieces before Wednesday's Champions League clash against Atletico Madrid.
The London side slipped from the top of the Premier League after conceding two soft goals from corners against Villa.
"Yesterday we worked on this particular situation," coach Carlo Ancelotti told reporters on Tuesday.
"It's difficult to train for set plays just like it's difficult to train for penalty kicks. But we worked on it because we have to improve.
"You can play a good match but if you don't pay attention once for six seconds you can get a bad result," the Italian added.
Germany captain Michael Ballack, returning to the side after missing the Villa game with an ankle injury, said the players had had harsh words for each other this week.
"We have no problem criticising each other in the dressing room," the midfielder said. "With a good team and strong players they have to do this. And we did it. After we shake hands and go back on the training pitch and get on with it."
Ballack said playing well and losing was particularly frustrating.
"It's one of our strengths that we are very well organised so it's a little bit unusual for us to concede two goals in one game," he said.
"It's all about individual mistakes and that happens in football. It shouldn't happen but it does. You can train many things but if somebody sleeps in a situation you concede a goal so everybody has to be aware of this."
Chelsea top Champions League Group D after two victories and Atletico are bottom with just one point.
"We have experience. We are in a good situation in the group and it's a home game. Everybody knows what they have to do tomorrow," Ballack said.
"It's a very dangerous game because Atletico have not started so well and need points. But we are a strong team, we've shown we can reach the semi-finals and we believe in ourselves."
Chelsea have reached the semi-finals of the Champions League in five of the last six years, losing the final in 2008.
Ancelotti urged caution against Atletico.
"They have a very good quality above all in the forward line with (Sergio) Aguerro and (Diego) Forlan. We have to play attention in dangerous areas. Aguerro can change a match with his quality," Ancelotti said.
Chelsea will be without right back Jose Bosingwa who picked up a knee injury on Saturday.
(Editing by Ed Osmond)