Andre Villas-Boas backs Chelsea defenders to fill John Terry void Under-fire Chelsea manager Andre Villas-Boas is confident Gary Cahill and David Luiz can form a solid defensive partnership during the absence of influential captain John Terry. Villas-Boas' position has come under intense scrutiny over the last few weeks after his team dropped to fifth in the Barclays Premier League and edged close to a Champions League exit after a 3-1 defeat against Napoli in the first leg of their last-16 tie on Tuesday night. To make matters worse for the Portuguese, he will now be without Terry for up to six weeks after he aggravated a long-standing knee injury. 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 during a period that is likely to determine whether the 34-year-old becomes the sixth manager to be fired by owner Roman Abramovich. 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. I am happy with Gary. He has been excellent in the games he has played. Cahill, who will line up against his old club Bolton tomorrow, 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 tomorrow 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. Chelsea ran out 5-1 winners at the Reebok Stadium in the reverse fixture at the start of October, when the Londoners looked set to challenge for the Barclays Premier League title after an encouraging start under their new manager. With his team now 17 points off the summit, Villas-Boas admits the differences between that meeting and tomorrow's could not be greater. That was maybe our strongest period of the season. The first three or four months were the best. Now we are colliding with maybe our worst period of the season," Villas-Boas added. In October Bolton's motivation was a little bit down due to the results they were having but they have turned it around a bit. I think it will be a difficult game now but we have this willingness to turn things around and hopefully we will win against Bolton. Fernando Torres missed training yesterday due to illness but is expected to be fit for tomorrow's game while Juan Mata is available despite suffering a suspected broken finger against Napoli.