Inter Milan boss Claudio Ranieri is battling to bring out the best in Mauro Zarate.

The Argentine joined the Nerazzurri on loan from Lazio in the summer, but he's struggled to impress at San Siro.

"He's a golden boy," the tactician told the Corriere della Sera. "He also has everything needed to be a champion.

"But I do sometimes despair. At times I realise that I need to throw him into a game, but he doesn't touch the ball, he doesn't chase opponents, he just watches the match.

"Then, the day after, he is a phenomenon in training. I then say to him: 'Why didn't you do that yesterday?'

"It saddens me, but I can't let him play with an earpiece in. Maybe it's my fault too, because I can't seem to find the key to get into Zarate's heart."