Messi bagged all four in a 4-1 win over Arsenal in the quarter-finals last season and Barcelona are hoping he is in similar form in order to overturn a 2-1 deficit from the first leg, with former Liverpool midfielder Mascherano claiming that Messi could be key once again.
"Nothing Leo does would surprise me. I think he can repeat what he did last year or even go one better. We don't know how far he can go,'' he told the Sun. "Obviously 1-0 is good enough but this team does not conform or settle for anything. We certainly will treat the game to win by the biggest margin possible."
Mascherano, 26, added: "We always play with the same intensity. The important thing is that we play in the way we are used to. Like we did in London, where I think that apart from the result it was spectacular.
"There are games where you don't deserve to have a negative result but you leave with almost nothing. Well, it's over now. But if we have the same intensity as we did in London we have a great chance to go through."
Argentina skipper Mascherano helped Barcelona record an important 1-0 win over Zaragoza on Saturday after making a rare start and insists that his side are not thinking about the injured Arsenal players who will miss the game at the Nou Camp.
"Walcott and Van Persie are two important players,'' he said. ''In Cesc's case I don't know if he will be there or not. In any of those cases they are very important players for Arsenal but also they have others to replace them.
"It's not as if we believe Arsenal will play with eight players if they're not there. No, they will play with 11. Maybe they won't be at the same level - but the ones who will come in, if they are at Arsenal it's because they have the level to be there.
"This is a hugely important game. Although it shapes the rest of the season in one competition we still have La Liga and the Spanish Cup as well. We all want to carry on and we will treat this game like a final."