The 34-year-old said the Blaugrana can overturn the two-goal deficit from the first leg, citing a mental strength both on and off the field.

"We have the recipe to come back and win," he told La Vanguardia.

"The team has come through some tough tests, not just in a footballing sense," Puyol added, referring to the recent illnesses to defender Eric Abidal and coach Tito Vilanova.

Barcelona have been criticised recently due to their lack of intensity without the ball, and Puyol admitted this aspect of their play needs to improve.

"We need to re-apply the pressure. The most important thing about this team is the reaction when they lose the ball."

And Puyol brushed off criticism over a perceived lack of unity in the dressing room, stating that the squad are as focused and professional as ever.

"People invent possible reasons for the defeats, but the dressing room is united. If they saw how we train, they wouldn't doubt us."

The second leg against Milan takes place at Camp Nou on Tuesday.