The Blues boss is set to put more emphasis on making his side hard to beat by changing personnel and formation after the 2-1 defeat at his former club West Brom. Chelsea have now conceded 18 goals in their last eight games in all competitions and collected two points from their last four Barclays Premier League matches.
The absence of Terry with a knee injury for three weeks after only just returning from a four game domestic ban has added to their woes ahead of Tuesday's away Champions League clash with Juventus. Di Matteo said: "Clean sheets certainly give you a chance to win games and we certainly have to improve on that side."
He added: "Defensively we just weren't good enough. Of course we miss John (Terry). He is an important player for us. He gives us a lot of confidence at the back and in general to the team. It's a shame that he is injured - but we will have to do without him until he comes back - and improve."
Di Matteo continued: "It's trying to find the right balance for us, whereby we can still create chances to win games. Maybe it's a time where we might have to change a bit in terms of our selections and the way we play but certainly we have to start with paying more attention defensively.
"Against West Brom, the first goal came from a cross and our defenders should have done better in dealing with that cross. We also had enough bodies in there to deal with the second goal as well."
Di Matteo is also conscious of Chelsea suffering their now accustomed decline in fortunes during November and the need to at least partially address their annual slump. After the trip to Turin, they entertain league champions Manchester City next weekend and can ill afford to lose if they want to remain realistic title contenders.
He said: "They are two massive games coming up we've got the players with a lot of experience.
"We've been in this position before but, for some reason, November for our club is a bad month and it seems to again be the case this year. we have to try and address that."