Croatia boss Nico Kovac rapped Mazzarri for criticising Kovacic after defeat to Juventus.
"Kovacic is only 19 years old, he is a young player with a lot still to learn," said Kovac.
"I have nothing against Mazzarri, as he too wants to help Kovacic grow, but against Juve the more experienced players ought to take on the greater share of the responsibility, not a 19-year-old.
"I expect great things from Mateo, but the criticism from Mazzarri was exaggerated. If Inter are in that position, then it certainly can't all be Kovacic's fault."
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