Chelsea interim manager Roberto di Matteo says his team need two "perfect" displays to beat Barcelona in the Champions League semi-finals.
Pep Guardiola's side, who have won the trophy in two of the last three seasons, travel to Stamford Bridge for the first leg on Wednesday.
"It's fair to say we need two perfect games," Di Matteo said.
"But the fact we've been performing very well gives us the belief we can produce two perfect games."
The Italian added: "It's the biggest challenge for any manager to play against the best team in the world. And it's a challenge for every player as well to be able to compare themselves against one of the top teams in the world."
Chelsea have won nine and drawn two of their 12 matches since Di Matteo took charge following the departure of Andre Villas-Boas, including Sunday's 5-1 win over Tottenham in the last four of the FA Cup.
But Barcelona's recent record is even more impressive as they have won 11 consecutive Spanish league matches and are unbeaten in 15 games - including their Champions League knockout-stage triumphs over Bayer Leverkusen and AC Milan.
The last time the two sides met was at the same stage of the Champions League in 2009, with Barcelona going through on away goals and Chelsea aggrieved at what they perceived to be refereeing mistakes.
"A long time has passed. I don't think they are playing for revenge," Guardiola said. "What you have lost, is lost. We will both be playing to try to reach the final in Munich.
"I admire this generation of Chelsea players. It will be exciting to play them.
"Chelsea have been inconsistent in the league but it will be different over two legs in a cup. I struggle to see how we can hurt them, how we can score.
"We shouldn't forget they've been very consistent here at Stamford Bridge, winning all five of their Champions League games."
As Cesc Fabregas prepares for his first club game in England since he left Arsenal for the Nou Camp last summer, the midfielder has revealed how he celebrated Barcelona's late equaliser at Stamford Bridge three years ago.
He said: "The previous night we'd lost the semi-final with Arsenal at Manchester United so I was still a bit upset.
"But I was at home with my family that night. We were about to play PlayStation [believing Chelsea were going through] and then that goal [by Iniesta] was scored.
"It was really happy memories because my whole family are Barcelona supporters."