The Rossoneri let Barça have the ball, but ensured they rarely got into the final third and struck with Kevin-Prince Boateng and Muntari to win 2-0.
"We played as a team, we listened to our Coach, he did a fantastic job in how he sent us on the pitch," grinned Muntari.
"We were very disciplined and managed to close every angle down so they couldn't penetrate us. If you play without concentration against them, they harm you and they make you suffer.
"It was the most important goal of my career. It is a good lead, but the Camp Nou is not easy. You can have a 5-0 lead but it is not safe as Barcelona have amazing players.
"We have two goals to our advantage and we will do our best to do well."