Branislav Ivanovic wants a clean sheet from Chelsea in their final Champions League group game against Steaua Bucharest.
Chelsea conceded after 13 seconds in their win against Southampton and have shipped six goals in their last two games - three against both Sunderland and Stoke.
Ivanovic played for 90 minutes in all of those matches and says Chelsea's uncharacteristic defensive lapses could affect his team-mates' confidence and stability.
The Blues have already conceded more Premier League goals than in their entire 2004/05 season, and need a win against Steaua to guarantee top spot in their group.
Ivanovic said: "As a defender, you are always worried when you concede a goal.
"It is always important to not concede a goal and to keep a clean sheet. This, game by game, gives confidence for defenders and gives the stability for the team.
"For us as a defensive line we will do everything to not concede a goal and try to do our best.
"In some goals we lost concentration. We conceded a couple of goals from set-pieces as well which is not usual for us.
"We know how strong we are in that part and we just have to get back to normal.
"We change a lot of small things for every game depending on the opponent. All these things have to work perfectly to not concede a goal."
Chelsea had been expected to progress from Champions League Group E with ease, but two losses to Swiss side Basel have left them not yet certain of finishing first.
Jose Mourinho's side beat already eliminated Steaua 4-0 in the reverse fixture and Ivanovic knows they need another strong performance to secure the group's top spot.
He said: "It is a very important game, especially because we had some defeats in the group and we want to finish top.
"We remember the game there. It came in a very difficult moment. We were concentrating on that game, that is why the result came for us.
"We have to be 100 per cent concentrated on this game as well, especially because they do not have anything to lose."