#1 Believe
"We must make sure their worst players get the ball the most. You’ll get it back in no time." - Johan Cruyff
More than anything tonight, Barcelona have to believe in themselves. No team has ever overcome a four-goal deficit in the knockout stage of the Champions League, but if there is any team that can do it, it's Barcelona.
Back in 2004, Deportivo La Coruna players produced the performance of their lifetime. After losing the first leg of their quarter-final to AC Milan 4-1, the La Liga side ended up winning 4-0 at home against the mighty Italians. They won the tie 5-4 on aggregate – completing one of the biggest upsets in the history of the competition.
In 2005, Liverpool did something very similar. 3-0 down at half-time, they went on to win the Champions League final against AC Milan. The difference? They scored an early goal in the 2nd half, put pressure on Milan's best midfielder – Kaka – and played a high-pressure game.
Barcelona have to do all that tonight, and more, to make sure that they make it into the next round.