The incident came with the Catalan giants 4-1 up against their La Liga opponents with 81 minutes on the clock.
Having scored one himself, hit the woodwork and created another goal for Marc Bartra, Messi was withdrawn by Martino in the closing stages. Spanish newspaper AS claimed the decision made Messi unhappy, and caused him to make his feelings known.
However, the four-time Ballon d'Or winner responded on his official Facebook page, branding the reports "media lies," per Drayton.
Nobody likes to be replaced, but we must accept it because it is the best for our team.
What I will not accept is that certain media tell lies about any situation that happens around me.
Messi has never appeared especially enthusiastic about leaving the field—as with most top players—and he has rarely been substituted during the past few seasons.
In 54 appearances last year, he departed prematurely in just four games, mostly as an injury precaution.
The season before, in 2011/12, during 78 appearances for club and country—across eight different competitions—amazingly, Messi was never substituted, as per Transfermarkt.
Fast forward to this current season and it's a different story entirely, with Messi withdrawn three times during the eight games he's played. A far higher percentage than in any of the previous years—albeit at a very early stage.
Martino previously went on record in August, as reported by Yahoo, saying he will not continually substitute Messi, but claimed the Argentine will need to be rested throughout the season.
Miles Chambers of Goal reveals Martino's quotes to reporters after the game:
Messi never wants to be subbed off, but it's my task to take care of him. We need him at end of season as well as now. My way of thinking won't change, I repeated the whole time how I want to play, maybe this game helps some to see things clearer.
Quite clearly Martino intends to restrict the time Messi spends on the pitch when a result is already wrapped up.
Having suffered a hamstring injury at a crucial phase of last season, this is a situation the Barca coach doesn't want to see repeated—although he will have his hands full convincing Messi.