Messi, who was on the scoresheet along with Dani Alves - the same scorers as in the first leg, believes his side showed just what they are made of in Wednesday's match.
He said: "We were coming off two very serious setbacks away from home (at Real Sociedad and Valladolid), but more so for the performances than for the results.
"Here we've returned to be the Barcelona that we want, that the fans expect.
"I don't know if the criticism was exaggerated or not. We're the first to be self-critical and we know we haven't done things well, we know when we've done badly.
"We lost the opportunity to continue being close to Real Madrid, but the league isn't lost whatsoever. There's a long way to go."
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