The Argentine is being linked with Juve this week.
"Gonzalo is a player who works really hard for the team," former Real Madrid and England manager Capello told Tuttosport.
"He doesn't just sit there and wait for the ball. He goes looking for it, comes back deep and allows others to push up into space, harassing defenders when they have the ball.
"As for when he's in the box, there's no doubt he is very talented and few have the same eye for goal as he does. He is world class."