Argentina captain Mascherano admits Messi drove the deal, urging Barca to buy him.
And Messi said: "He's a great player. In addition to what he can do in football, his arrival is a joy for me. Barcelona wanted him for what he means as a player and as a person, I am very glad that he signed."
He added: "He's a great player, he really helps us, hopefully this season we can keep winning titles with Barcelona's shirt."