With Barcelona now within touching distance of a second consecutive Champions League final, Messi said: "It's a joy, because the team had started badly and ended in a spectacular way and it is a thrill to feel the happiness of the fans.
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He added that the Champions League "is a very important competition" and that Barcelona have before them a "great opportunity to repeat the title."
Before the showdown with Jose Mourinho's side, however, Messi and Barcelona take on Real Madrid at the Bernabeu in a match that could decide the Spanish title.
Looking ahead to the weekend, Messi said: "The important thing is to continue in this way, we have a big game on Saturday. It will be difficult to repeat [what I did today but] the important thing is to win, even if it is 1-0."
The 22 year-old's goals last night saw him become only the sixth player in the history of the Champions League to score four times in a single match and took his season's goal tally to 39 in all competitions.