Former South African all-rounder Jacques Kallis feels that the India captain Virat Kohli needs to tone down his on-field aggression. Kallis said that Kohli's aggression is working for him, but he should also see if it works for his team as well. "He has been aggressive and I think it works for his game. But it maybe an area he needs to look at. The way it works for him, he has got to see if it works for his team. It might be an area to tone it down a little bit,” said Kallis.