But Chelsea boss Conte believes if his side keep their heads and execute their game plan like they did last night, they can upset the odds.

"It won't be easy, we must be realistic, we are talking about Barcelona," said the Italian.

"But we have showed that if we are ready to work hard together defensively and at the same time continue to have the right feeling when we have the ball, to have the chance to score, then we can try to do something incredible.

"You have to respect the opponent, in this case when you play Barcelona box to box you know very well you are crazy and you can lose the game 4-0, 5-0 or 6-0.

"When you play this type of game you must use intelligence. You must play an intelligent game, and we are not stupid."

Willian had rattled both posts in front of The Shed in the first half, but he made it third time lucky on the hour, pinging a low shot into the bottom corner.

However, Barcelona hit back with 15 minutes remaining, punishing the first mistake of the night from the Chelsea defence.

Conte, who revealed he had been having trouble sleeping ahead of the match, will be having nightmares about the equaliser.

Andreas Christensen's suicidal pass across goal allowed Andres Iniesta to cut the ball back for Messi to score against the Blues for the first time in nine matches.

The visitors predictably dominated possession, racking up 73 per cent while making 887 passes to Chelsea's 325.

But Barca coach Ernesto Valverde said: "We still have to be respectful of their style of play. Anything can happen.

"Yes we passed the ball more. But they pressed us high and they made life very hard for us.

"The away goal is not definitive but it is important, yes."