However, the Italian admits he feared Hazard was going to quit Chelsea this summer.
He said: “Chelsea – one of the most important clubs in Europe – cannot sell an important player, without the possibility of buying one on the same level. Of course, I was concerned about this problem.
"But after the first time I spoke to him, I was sure he would stay. So I was concerned for 20 days, no more. Now I am sure Eden will be with us for the season.
“We are talking about one of the most important players in Europe now but, in my opinion, he can improve more.
“He can be the first. It depends on him. The best for technical skill, the best for scoring, but I think it depends only on him. On his mind.
“The World Cup players are working with me very well, more than with the others. They are not completely ready to play 90 minutes. But against Arsenal, we can see one or two in the first part of the match, and one or two in the last part.
“Hazard, technically, is really one of the best in Europe in this moment. He has to work from the physical point of view, of course."