Messi scored the winning goal in Argentina's World Cup opener against Bosnia-Herzegovina after coach Alejandro Sabella had reverted to a 4-3-3 system, following his side's laboured approach in a 5-3-2 set-up in the first half.
The Barcelona star said earlier this week that the Albiceleste should stick to their favoured system going forward, prompting suggestions that he was unhappy with his coach and even that he is involved in choosing the side for matches.
Mascherano, however, has rubbished the reports, claiming Messi would simply be unable to pick one team-mate over another for the starting line-up.
"I know Leo Messi well. He would be incapable of adding or replacing a player. It's not his way of being. He's a guy who would never chose between one or another of his friends," he told Ole.
"He's not like that, he doesn't feel that. And he would feel bad doing it...
"Plus, there's a coach who decides. And he would be totally disrespecting Sabella."
Mascherano also insisted it was entirely the choice of Sabella and the coaching staff to revert to a 4-3-3 formation against Bosnia-Herzegovina.
"Obviously he [Sabella] decided it," added the Barca defender. "Besides, in the middle of the game, it would be very difficult for a player to realise it. He spoke with his colleagues for a while and then explained how we should follow."