Former Barcelona assistant coach Angel Cappa suggested this week that the Argentina forward, who has recently been hampered by injuries, had lost his passion for the game.
Sevilla coach Unai Emery claimed such comments could awaken "the beast" inside Messi and that prediction appeared accurate as the 26-year-old netted twice in a 4-1 win at the Ramon Sanchez Pizjuan.
Martino retains full faith in Messi and feels he has answered all of his doubters.
"What happens is they [critics] touch his honour, but the next opponent usually pays for that, not the critics," said Martino.
"Messi is always decisive, no matter what position. Sometimes he just draws people to the centre which gave us space on the wings."
Andres Iniesta also voiced his support for Messi after Barcelona moved back to the top of La Liga.
He added: "Leo is never missing; he's one of the very few players when given a couple of seconds or a couple of metres, he can change the face of the game.
"He does that every day and he did it today as well.
"It was important to get the win and move back to the top of the league.
"We lost the lead for six days and it didn't take long to get it back. The conditions weren't the best but we did it."
‘Chelsea have to qualify for the Champions League for this season to be a success – they showed that they have the players to perform at a high level, they need a win quickly now’ Blues legend’s fears over recent bad run
'I’d probably pick Cole Palmer alongside Bellingham and Rice in there at the moment. For me, Declan Rice is good enough to play that central midfield role on his own' Thomas Tuchel advised to DROP Manchester City star by England legend
