Roberto De Zerbi says he has no timescale on Levi Colwill's enforced absence.

But he has spoken of a wish to keep the on-loan Chelsea defender with him for a longer period.

Colwill is currently out with a muscular problem.

De Zerbi said: “It’s an important injury.”

The head coach has been impressed by Colwill and the left-sided option he gives.

He added: “I am sorry for him because, for us, the left centre-back is very important.

“Lewis Dunk is a top player but he is on the right and we lose some line passes from the left.

“I am very happy with Levi’s progress.”

De Zerbi had not yet caught up with Facundo Buonanotte as he spoke to media yesterday.

But he is confident the Argentinean did not suffer serious damage in South America.

Buonanotte left the CONMEBOL Under-20 Championship early after a heavy fall when he challenged for a high ball.

De Zerbi said: “He is injured but, sincerely, I don’t know what is the problem or how long he will be out.

“But I think not so bad the injury.”