With Jose Bosingwa also sidelined, Villas-Boas will have no other option than to put his faith in new signing Cahill and the erratic Luiz at the back and the early signs do not look good. The team have conceded seven goals during the three games when Cahill and Luiz have started together in the centre of defence, but Villas-Boas has faith in the duo.
"At the moment we have a new partnership that we are trying to fine tune to be more stable at the back, like we were in January," Villas-Boas said. "Both of them are very extrovert, Gary speaks a lot, organises a lot. It is not about communication. It just takes time, it's a new partnership and you have to get used to the person next to you."
Cahill, who will line up against his old club Bolton on Saturday, has told his manager not to expect too much too quickly, however.
"There have been changes made so it's not something that will click right in to place straight away," Cahill told Chelsea TV.
"It's different. The full-backs have changed so I'm not going to lie and say it's fantastically easy.
"We have had some sticky results of late and I have been plonked straight in the middle of it all so it's been difficult, but the more work we do on the training ground the better it will be."
Cahill revealed the squad are desperate to bounce back from the midweek loss and deliver the manager a win against Owen Coyle's team at Stamford Bridge.
"Training has been really sharp. The lads got back to work really well," Cahill added.
"We have to be determined to bounce back with a win. Saturday is a big day for us and when you have results like (the one in Naples) sometimes the best thing you can hope for is fixture straight after."
Source: PA
Source: PA