"Now, all I can say about Carlton is that it all depends on him, because he has all the qualities.
"He is strong, he is quick, he is technically very good, so if he keeps focused on what he is doing, then of course he can be there.
"Capello knows him and certainly is keeping an eye on him."
Zola added: "I can see improvements and I am sure that he knows that, if he wants to play for England, he will have to work even harder, because the people who are playing in his position are also doing well.
"Obviously you can't ask him for everything straight away, but he is working on his game and knows there are areas that he needs to improve.
"He knows that finishing is one of the things he has to improve, but in the last year he has been much better.
"He needs to work on his consistency and to keep scoring continuously, and that will be good for his confidence, for his game and for me.
"We just need to give him the time and tranquillity necessary to produce the results."