Chelsea is missing John Terry after the club's defensive problems deepened ahead of Saturday's Premier League game at Swansea, manager Roberto Di Matteo said Friday.
"He's obviously been an influential player for us, for sure, and a fantastic defender," Di Matteo said. "When he plays, he's always played very well for us. The other players have done a fantastic job by coming in and playing when they've been in the team but, certainly, JT is a player that we miss."
The European champions were all over the place at the back Wednesday and were hardly any better in Sunday's first league defeat of the season against the same opponents.
Chelsea has now conceded 11 goals in just four games since Terry began his domestic racism suspension, though the Chelsea captain did play in one of them when he started their Champions League defeat at Shakhtar Donetsk.
While Terry serves the final instalment of his ban Saturday, Di Matteo revealed fellow defender Luiz would almost certainly miss the Swansea game because of an ankle injury.
Luiz's absence would mean Branislav Ivanovic would be pressed into center back service in a new-look defense that would almost certainly see right back Cesar Azpilicueta handed his full league debut, with Ashley Cole returning from injury on the opposite flank.
Some would argue any defense without the erratic Luiz would be an improvement, but it is the absence of Terry that has been more cause for concern.
"The last few games, we've conceded a few more goals than at the start of the season," Di Matteo said. "Generally, it's been down probably to a few individual mistakes. But I think our track record is very good and, surely, will continue to be."
If not, Chelsea can surely forget about staying top of the Premier League and reaching the Champions League knockout stages.
"We have to improve but I don't think it's just as simple as that," Di Matteo said. "You look at other teams and they're conceding goals, so we certainly have to improve, from the last few games, our defensive organization."
It is not just at the back where Chelsea have problems.
Fernando Torres and Daniel Sturridge both look well short of being the kind of ruthless finisher that would ease the pressure on the defense, leaving Chelsea to rely more and more on its much-vaunted trio of Mata, Oscar and Eden Hazard.
Mata's goals and assists, in particular, have been absolutely vital, so the news that a hamstring injury would almost certainly put Mata on the sideline with Luiz on Saturday was another blow.
"A few others have a few niggling injuries as well, so we'll have to see for tomorrow," Di Matteo added.
Throw in the Mark Clattenburg controversy, and a match Chelsea might have been expected to win reasonably comfortably tomorrow suddenly looks a much more difficult proposition.
"We are okay," Di Matteo said. "The team is playing well, despite one defeat that we had in the league."
Acknowledging the importance of Wednesday night's thrilling comeback, he added: "It was a great win for us, for the spirit of the group as well. Winning is always a good factor for the team and for the group. I think we showed how strong we are and that we can compete against any other team."
Information from Press Association was used in this report.