The club's fans are more than happy to overlook the fact he has never scored in nearly 300 appearances, because few players are as important to the Spanish champion.
Having already proved his flexibility over the years, the 32-year-old Mascherano is now learning another position.
Mascherano is defying his age and increasing his worth in a team whose intricate passing style is incredibly demanding on players. The Argentina international has become coach Luis Enrique's fix-it man.
Already able to play either in midfield or as a central defender, Mascherano has now passed the test as Barcelona's right back.
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Enrique said on Friday that Mascherano may play on the flank for Saturday's visit to Valencia in the Spanish league. "The option of Mascherano is open," said Enrique, who rarely reveals his lineups before the match.
"He played a good match against City and he is one of the possibilities that I have for this and other matches."
Wherever he plays at Valencia's Mestalla Stadium, Mascherano will be tasked to hold down a back line that will be without the injured Gerard Pique and Jordi Alba.
Mascherano's value is his versatility and willingness to sacrifice in a team full of incredibly talented individuals such as like Messi, Neymar, Luis Suarez and Andres Iniesta.
It was Guardiola who gave Mascherano the first opportunity to reinvent himself at Barcelona when he was struggling to find a starting role.