The Argentine believes that Barca could have scored more goals against the Rossoneri, and added that he has no preference as to who the Catalans will meet in the final four.
The Catalans recorded a 3-1 win in the second leg after being held to a scoreless draw last week, and Mascherano feels that Barca could easily have won by a more significant margin.
"In general, we put in a great performance in defense despite conceding a goal. The match could have ended with a much bigger difference," Mascherano was quoted as saying on the club's official website.
"This is how the coach prepared the match. We had to create a lot of chances and we knew that we had to score a lot of goals. We started with a 3-4-3 because we needed players that would stretch out the field because Milan defend really well."
Barcelona will meet the winner of the quarterfinal between Chelsea and Benfica in the last four, with the Premier League side defending a 1-0 lead from the first leg.
However, Mascherano has insisted that he does not have any preference which opponent the team will face.
"I hope we can make it to our third final in four years," he said. "It would be great for the club and for the players. We need to be mentally strong. Regardless of who we have to play, whoever makes it to the semifinal deserves to be there and they will be difficult to beat. I have no preference."
The Blaugrana resume La Liga action on Saturday when they take on Zaragoza.
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