Branislav Ivanovic hopes Chelsea's defence can find their mean streak again after gifting goals to the opposition in early December.
The Blues will bid to claim top spot of Champions League Group E by beating Steaua Bucharest at Stamford Bridge on tonight.
Jose Mourinho's men conceded after 13 seconds in the win over Southampton in their most recent home match, before letting in six goals during the two Premier League matches since that victory.
Ivanovic struggled to explain the uncharacteristic defensive lapses which mean Chelsea have already conceded more goals in the Premier League this term than in the whole of Mourinho's first campaign as the club's boss, in 2004/05.
"As a defender, you're always worried when you concede a goal," Ivanovic said.
"It's 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 defence 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."
"We have to kill opponents. We have to score goals. We are also conceding goals defensively" Jose Mourinho
On paper, it appeared 2012 Champions League winners Chelsea would have a straightforward passage to the last 16 when Group E was drawn.
An opening loss to Basle piled on the pressure and Chelsea responded by winning 4-0 in Bucharest and twice beating Schalke before losing in Switzerland, but still qualifying.
If Basle beat Schalke and Chelsea can only draw with Steaua, the Swiss would go through as group winners on the head-to-head record.
Ivanovic insists Chelsea must secure top spot by winning against already-eliminated Steaua at Stamford Bridge.
"It's a very important game, especially because we had some defeats in the group and we want to finish top," the Serbia defender added.
"We remember the game there. It came in a very difficult moment. We were concentrating on that game, that's why the result came for us.
"We have to be 100% concentrated on this game as well, especially because they don't have anything to lose."
Mourinho admitted his frustrations with his team, with the 4-3 win at Sunderland followed by a 3-2 loss at Stoke.
The Portuguese is annoyed by shortcomings up front and in defence, admitting even the training aids would have the good fortune to score against his side at present.
Mourinho said: "We have to kill opponents. We have to score goals. We are also conceding goals defensively.
"In this moment if you train defensive corners against the dummies, I think one dummy will score, because all the rebounds they go to the opponents."