El Pais reports that the moment took place following Barcelona's 1-0 defeat in January against David Moyes' Real Sociedad side.
At the time, the Catalan giants looked like being outshone by Real Madrid throughout the season - a situation not helped by the simmering feud between Messi and manager Luis Enrique.
Xavi is said to lost his temper at the diminutive Argentine - a player he has known since Messi moved to Barcelona aged 12.
"'We can't allow ourselves to repeat what happened last season and you know it," Xavi apparently told Messi.
"Do you want Cristiano to win the Ballon d'Or again? Stop f***ng around, Leo!"
Since that fateful day in San Sebastian, as El Pais reports, Barcelona have recorded 27 wins, one draw, one defeat, and have score 94 goals.
Even Messi himself admitted back in February that "after the Anoeta [Real Sociedad's stadium] everything changed."
Enrique, meanwhile, has his own method of taking the temperature at the club: "I always take note of how the players on the bench react to a goal to see if there's a positive spirit in the squad, and right now the atmosphere is perfect, marvellous."
So too are Barcelona's prospects of a treble. As the Daily Mail's Rob Draper puts it, "what you see now - Barcelona as league champions, favourites for the Champions League and the Copa del Rey and Messi arguably in the form of his life - may be a direct result of that conversation."
source:eurosport