Di Matteo has transformed the fortunes of the Blues since being appointed caretaker manager just over six weeks ago, culminating in Sunday's 5-1 FA Cup semi-final thrashing of Tottenham.

But the 41-year-old had no illusions Chelsea would need to hit new heights tomorrow and next Tuesday to beat the team some regard as one of the greatest of all time.

"It's fair to say we need two perfect games," Di Matteo said.

"But I think, also, that the fact we've been performing very well in the last six weeks gives us the belief we can produce two perfect games in this match.

"It's the biggest challenge for any manager to play against the best team in the world, but for every player as well, to be able to compare themselves against one of the top teams in the world."

Chelsea have every incentive to conjure up the perfect performance, with a Champions League final and the chance to avenge their semi-final defeat of three years ago the prize on offer.

But Di Matteo denied the burning sense of injustice from the sides' last meeting - which saw the Blues denied a clutch of penalties before Andres Iniesta scored a stoppage-time away goal - would be a motivation tomorrow.

"What happened in the past has gone," he said.

"There's a strong feeling in the team that they want to do well, that they're highly motivated to produce a good performance against Barca."

Chelsea have proven Barca's bogey side down the years, helping thwart their Champions League ambitions on more than one occasion.

Di Matteo said: "They don't like to play against us.

"The results in the past show that. The way we play is maybe a bit more difficult for them to play against.

"We respect each other, both, but we both know there'll be two teams tomorrow night who will play against each other.

"We've shown on many occasions that we're a team who can give them a lot of problems."

Things have changed since Chelsea last played Barca, not least for Lionel Messi, who has established himself as one of the all-time greats.

The 24-year-old has never scored against Chelsea, but had only 78 career goals the last time they met and now has a whopping 243 - 63 this season alone.

Di Matteo said: "It has to be a collective team effort and responsibility to stop him.

"If you just think about stopping one guy, they've got nine others who can hurt you.

"The tactic has to be not just to stop one player, but to limit their threat in general rather than just Messi."

He added: "It's going to be a game where we obviously have to make sure we don't concede, but we also have to try and score a goal or two as well if we can to go into that second leg with a good result."

The Blues could also do with a referee who does not deny them the kind of penalty claims they had snubbed in 2009.

Di Matteo said: "I have no fear, absolutely not, that there'll be anything at the back of (the referee's) mind."

Chelsea suffered a blow tonight after Di Matteo confirmed defender David Luiz would miss both legs with the hamstring injury which forced him off in Sunday's FA Cup thrashing of Tottenham.

"It's a big loss for us," Di Matteo said.

"He's a fantastic centre-half who was in good form. We hope to get him back in two weeks, maybe, and hopefully he will be ready for the end of the season."

Di Matteo faces the biggest selection dilemma of his fledgling managerial career tomorrow as he tries to juggle his resources during a punishing schedule in which every game is crucial.

His most difficult decision tomorrow looks to be whether to start Didier Drogba or Fernando Torres.

Praising both, Di Matteo said: "I still have a few doubts in my mind about the team selection.

"But a good night's sleep does good sometimes. I will decide tomorrow morning."