Lazio coach Davide Ballardini insists Mauro Zarate is a bigger threat than Juventus star Diego.

"Both of them are fantastic players, albeit different," he said ahead of Saturday's top of the table showdown.

"It would be wonderful to see them play together, but if I had to choose, then I would keep Maurito. He has improved so much in coming back to help the midfield and he passes the ball more often.

"I do not intend to change his characteristics, but it is only with this new attitude that he can become a phenomenon.

"For now he is just a great player, as I often tell him, but with the right approach he will become one of the best in the world."