Di Matteo's side are firm favourites to advance to a last four clash against Barcelona after Salomon Kalou's second half strike clinched a 1-0 win over Benfica in the first leg last week.
Benfica posed little threat to the Blues in Portugal, but Di Matteo is adamant the Lisbon club are capable of upsetting the odds at Stamford Bridge, especially if Chelsea produce the kind of sloppy defending that almost gifted Aston Villa a draw on Saturday.
Di Matteo's men conceded twice in three minutes late in the match before eventually running out 4-2 winners at Villa Park and the Italian is determined to stamp out that kind of complacency ahead of the Benfica showdown.
"We won't switch off. Only 50 percent of the job has been done because qualification is over two games," Di Matteo said.
"We have put ourselves in a good position but Benfica away from home are a very strong side and they are capable of scoring as well so there will be no complacency from our side at all.
"I think we've been battling very well in the last three weeks, we have shown that on several occasions.
"The reaction after Villa drew (level) was fantastic from the team because we could have capitulated, but we went the other way and had this strong desire to win the game."
Di Matteo's calm and understated leadership has helped Chelsea get back on track with six wins in the eight matches since he took over from Andre Villas-Boas.
While Villas-Boas became embroiled in power struggles with several senior players in a bid to stamp his authority on the dressing room, Di Matteo has managed to keep those stars onside to such an extent that some are calling for him to be given the job on a permanent basis.
Even difficult decisions like leaving Frank Lampard on the bench for the first leg against Benfica -- the kind of gamble that proved so costly for Villas-Boas when he attempted the same thing in the previous round at Napoli -- have proved successful.
Lampard had a strained relationship with Villas-Boas and he admits Di Matteo's approach has been a breath of fresh air.
"I spoke with Robbie and certainly had no issue with it. I was delighted to get the result we got," Lampard said.
"The manager makes the decisions and he is revelling in making those decisions.
"He has kept it very simple. It's a case of getting a confidence and passion through the team and, in the results we've had, you'd say he has done that.
"There's a lot to be said for having a confident squad. You have to have that to get the best out of all your players and I feel we are in a better position now than we were in the past."
However, Di Matteo, who had previously worked as Villas-Boas's assistant, is keen not to take too much credit for the revival.
"I don't want to talk about the past. We can only look forward," he said.
"I am pleased with the attitude of the players, they have shown great character as well.
"We are in this difficult situation, the season has proved difficult for us and we are just trying to win our games now."
Di Matteo will hope Brazilian defender David Luiz can recover from an ankle injury in time to face his former club, while Ivory Coast striker Didier Drogba is also a doubt with a foot problem.
Meanwhile, Benfica boss Jorge Jesus is convinced his team have the quality and courage needed to cause a massive upset in west London.
"We were superior in many things to Chelsea (in the first leg), but they were luckier in one moment," Jesus said.
"We've scored in all our away games so far, so we can easily go there and win."
Source: AFP
Source: AFP