Barcelona coach Pep Guardiola has warned his players to forget last week's impressive performance against Arsenal at the Emirates stadium and focus on the job in hand when the two sides meet again at the Nou Camp tonight.
Barca played Arsenal off the park with some breathtaking football in the first half and went 2-0 up early in the second period.
The Catalans were eventually pegged back, though, and had to settle for a 2-2 draw as Arsenal rallied late on.
It was perhaps an unfair reflection of the play, which Barca dominated, creating 22 chances overall and an incredible 11 in the first 15 minutes.
But Guardiola says a repeat of that performance cannot be expected tomorrow.
'What we did the other day has nothing to do with tomorrow's match,' Guardiola said.
'Those things only happen every now and again and it's in the past. We have to forget about it and focus on doing our job tomorrow.
'We performed well last week but now we have to go again and if we don't play well, if we do not produce the necessary level of performance, it will be tough and we might not get to the semi-finals.'
Guardiola is missing a host of first-team players with defensive pair Carles Puyol and Gerard Pique suspended.
Zlatan Ibrahimovic, who scored Barca's goals at the Emirates, is also out after picking up a calf injury in the warm-up ahead of Saturday's 4-1 win at home to Athletic Bilbao.
'It's bad news because he is a very important player for us, so we hope he recovers as soon as possible,' Guardiola said.
The Barca coach will also make a late decision on Andres Iniesta, who was out with a thigh problem but is now back in full training.
Arsenal boss Arsene Wenger called on his battle-weary side to show no fear as they aim to upset the odds.
The Gunners' preparations for the second leg were today hit by the news Cameroon international Alex Song - who had been in line to drop back into defence as veteran Sol Campbell struggles to regain full match fitness - was out with a knee injury.
Arsenal were already missing captain Cesc Fabregas, who suffered a cracked bone in his leg when winning the late penalty which levelled the tie at 2-2, as well as centre-back William Gallas and Russian playmaker Andrey Arshavin.
However, Wenger maintains his team - with England forward Theo Walcott in contention to start having made a major impact from the bench in the first leg - have what it takes to pull off another famous away victory.
'We have won away everywhere in Europe. Barcelona is a place where we have not done it, so there is no better opportunity than tomorrow night,' Wenger declared.
'I am confident despite the injuries we have that we can do it. Of course, we will need to get everybody to 100% of his potential and have a great team performance.
'This team, though, has such a great mental strength and I believe they can fight against the odds anywhere in the world.'
Wenger openly admits Arsenal are lucky to still have a chance, however slim, of progression to the semi-finals after the way in which they were completely dominated in the opening stages of the first leg.
'We have learned that it is important we start will full power, without any inhibition, which we showed in the first 20 minutes at the Emirates,' he said.
'How we manage to do that will certainly have a big influence on the game and on the result tomorrow. We have to try to be very disciplined, but not to hide when we have the ball.'
With so many of his key men missing, the last thing Wenger needed was another injury problem.
The prognosis on Song, however, does not look promising.
'It was a bad surprise this morning, because he had a scan yesterday afternoon on his knee and it is an inflamed cartilage,' the Arsenal boss revealed.
'We have to wait how the evolution will be, but he is completely out of the squad for tomorrow's game.'
Song had been pencilled in to drop back into defence, as he had done following Gallas' calf injury relapse in the first leg, given Campbell can often need more recovery time between games.
Wenger will, though, leave a decision on the 35-year-old's involvement as late as possible, with fellow veteran Mikael Silvestre, 32, also part of the 18-man squad which left Luton this afternoon.
'That is a decision I have to make, consulting with Sol tomorrow (Tuesday) to see how he feels,' Wenger said.
'Today he was still not completely available. He managed a warm up and then we got him in. It is such a big game that you must be completely fit or not play at all.'