Messi struck all three of Barca's goals in the 3-1 first-leg win at the Vicente Calderon and later said: "It was a beautiful night, it always is when you go to another stadium and the fans treat you well. I am grateful to the Atletico supporters, who thanked me with their applause.
"I'm happy for the victory, although we know that there is another leg to play in this tie.
"We have taken an important step. We proved once again that no matter who plays, there are 24 players in the squad capable of winning."