The forward's ex-fitness coach in the Argentina set up, Fernando Signorini, says there's no question of the 26-year-old losing his hunger for the game.
Messi was criticized following Barca's 3-2 defeat at home to Valencia the previous Saturday and former Blaugrana assistant Angel Cappa claimed the 26-year-old had lost his passion for the game.
But Messi reacted with two wonderful goals in the Catalans' 4-1 win at the Sanchez Pizjuan and Signorini claims the Argentine was "licking his wound" following Cappa's controversial quotes.
"When a feline has a problem [injury], he can't go immediately in search of the prey because he will do himself damage again," the Argentine told Catalan station La Xarxa. "And Messi, to summarize, is a feline licking his wound: he is just waiting for the right moment to attack and pounce like he did on Sunday, when the team needed him and he scored two goals."
Signorini believes the last thing Messi will lose is his passion for football and claims the 26-year-old's movement on the pitch has been restricted by his recent injury problems.
"I think he would lose his passion for eating before he lost his passion for football," the fitness coach said. "A footballer never loses that desire. He uses such a large amount of movements and muscles that aren't used in other sports. He has to react instantly on the pitch and he also has the burden of discovering the dreams of millions of fans.
"Being a good footballer is very complex and even more so when you are a martian like Messi."