The whistle blew, the dust settled and Barcelona left the San Siro with heavy hearts.
After the 2-0 loss to AC Milan, the Catalans have a huge test on their hands to advance to the next round of the Champions League.
With the return leg being played at the Camp Nou in a few weeks, Barcelona has a lot to fix if they want to get to the next round.
It was very obvious that not only did Barcelona lose, but they were dominated. Milan implemented their defensive plan and executed it to perfection.
But not all hope is lost for Barcelona. History can always be made, and with 90 minutes to mount a comeback in Catalonia, do not count Barcelona out yet.
In this article we will take a look at the five keys to Barcelona overturning the odds against AC Milan.