Barcelona will have to play one of their best games of the season if they are to keep their hopes of staying in the Champions League alive when they host AC Milan in the last 16 second leg.
Barca are down 2-0 after the first leg and with Milan in buoyant mood, face a very difficult prospect at the Camp Nou.
"The perfect match will be the one that ends well and takes us to the quarterfinals," Barca assistant manager Jordi Roura said. "We have to find the right balance between intensity, strength and haste. This match will last 90 minutes so we have to keep our heads and keep our cool, not lose control of the match.
"We have all seen lots of games similar to this situation but every match has its own peculiarities. In the end we have to focus on how we play, but perhaps we have analysed the first leg against Milan more than any other match. Tomorrow (Tuesday) is very important, not just for me, but for the club, the fans and the team as a whole."
Barca will have to keep their recently leaky defense tight, because conceding a single goal against Milan will mean that the home side will have to score at least four to progress.
"I expect Barcelona to put us under a lot of pressure from the word go," Milan manager Massimiliano Allegri said. "They are very capable of turning the tie around. They create lots of chances to score, so you have to be good on the ball and determined when you are defending.
"We may have few chances to score but they are likely to leave gaps in their defence. When you face Barcelona you're never calm. I think they will try and score an early goal, but we have to keep calm."
Barca are likely to welcome back Xavi Hernandez, who has missed the last couple of games with a hamstring problem, while Milan face a bigger problem with both of their forwards Mario Balotelli (ineligible) and Giampaolo Pazzini (fibula) ruled out.
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Expected lineups: Barcelona: Valdes; Alves, Pique, Puyol, Alba; Busquets, Xavi, Fabregas; Pedro, Messi, Iniesta.
Milan: Abbiati; Abate, Mexes, Zapata, Constant; Ambrosini, Montolivo, Muntari; Boateng, Niang, El Shaarawy.
Prediction: 3-1 to Barcelona