Barca are in Madrid for the second-leg with the scores locked at 1-1.
Martino said: "We're accustomed to Messi scoring a goal per game. If he doesn't score, we all take notice. What we want is for him to be decisive, but that doesn't mean he has to score," said Martino, who added that the forward "has been decisive for the team in 2014, he's had the continuity that he hasn't had before and it's clear that he'll always be decisive for Barça."
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